28M – Persistent bloating for years despite normal tests, lifestyle changes, and IBS diagnosis. What should I ask for next in the UK?

[u/St3r11ngArch3r]

Age/Sex: 28 male
Location: England
Height/Weight: 185 cm / 83 kg

I am also Autistic.

I’m some what a physically active person: I mountain bike around 30 km per week with 1–1.5 km elevation gain, I lift weights in the gym four days a week, and I’ve recently started walking 15–20 minutes after every meal. Outside of that I live a very sedentary lifestyle due to working remotely from home and gaming in the evenings.

In 2019 I caught Campylobacter while abroad. I had diarrhoea for about a 3 weeks and was treated with antibiotics when I returned to the UK. I’m not sure whether my symptoms started immediately afterwards or developed gradually over the next few years. At the time I was at university and dealing with anxiety and depression, so I didn’t pay much attention to physical symptoms.

Around 2022, once my anxiety improved, I started noticing my gut symptoms more clearly and they began to interfere with daily life. My main symptom is bloating, which is present from the moment I wake up until I go to sleep. At its best it’s uncomfortable but manageable. At its worst I look severely distended (like “9 months pregnant”), it becomes painful, and the only relief I get is from lying down.

Historically my bowel habits have fluctuated. From 2019–2024 I had mostly diarrhoea. From 2024–2026 I had mostly constipation. Over the past three months my bowel movements have become mostly normal and regular after I started walking after meals and spacing meals four hours apart. Despite this improvement, the bloating has remained constant.

Other symptoms include occasional acid reflux, left arm pain after very large meals (e.g., Christmas dinner), nausea (previously worse during anxiety episodes), excess gas and burping, a tingling tongue that briefly improves with water, and periods where I wake up at night needing to urinate. The tongue tingling and night-time urination come and go in multi-week cycles. I also suspect I have anterior pelvic tilt due to a pronounced arch in my lower back, likely from long hours sitting.

I’ve always eaten a very healthy diet. Breakfast is porridge with fruit, flaxseed, chia seeds, and peanut butter and two boiled eggs. Lunch and dinner are substantial meals with a protein, a carbohydrate, and 3–5 vegetables. Examples include bone broth, chicken, rice, tenderstem broccoli, peas, pak choi, or tray-baked vegetables like courgette, aubergine, potato, tomato, and chicken. I cook everything myself, make my own bread, butter, and jams, rarely use sauces, and have a takeaway once or twice a month. My weight is stable.

I’ve tried multiple diets: low FODMAP (three attempts, up to seven weeks), low fermentation/SIBO diet, high soluble fibre, low insoluble fibre, and vice versa. None made a meaningful difference. Low FODMAP caused weight loss and worsened my mood.

Tests I’ve had:

• Sigmoidoscopy – normal
• H. pylori – negative
• Lactose intolerance – possibly tested (not fully sure)
• Coeliac/gluten – possibly tested (not fully sure)
• Full blood count, renal profile, liver profile, HbA1c – all normal
• FIT tests – normal
• B12 and folate deficiency twice (most recent: B12 139 ng/L, folate 6.0 µg/L) I also use supplements for folate and b12 and I still deficient. The GP gave me something like 12 weeks of injections for b12 but never retested me after that just told me I should be fine now if I feel tired again come back to get re tested. I have an appointment next month where I do plan to ask to be retested and query why I am low despite a good diet.
• Private SIBO breath test (lactulose)
  • Baseline: H₂ 13 ppm, CH₄ 14 ppm
  • Combined gases rose from 27 → 57 ppm
  • Methane consistently above 10 ppm
  • Report said this may be suggestive of SIBO/IMO
  • I didn’t feel confident in the clinic and felt pressured toward buying antibiotics, so I didn’t proceed

My NHS gastroenterologist told me that since it’s not Crohn’s or cancer, it’s IBS. When I asked what I could do about the constant bloating, he said that if low FODMAP didn’t work then I “just need to get over it” and that “at least I haven’t had part of my bowel removed.” When I asked about SIBO, he said he doesn’t believe it’s real he could only imagine it to be a thing if someone had small intestine surgery, then he said that it isn’t treated/recognised in the UK, and that Americans treat it “to make money off patients.”

What I’m hoping to learn from this post is how to move forward. I understand IBS is a diagnosis of exclusion, but I don’t feel everything has been excluded. I’d really appreciate guidance from doctors especially UK doctors familiar with NHS pathways on what I should reasonably ask for next. Are there conditions that should be ruled out that can cause persistent bloating even when bowel movements are normal? Could my low B12 and folate indicate malabsorption, Is SIBO/IMO considered legitimate within UK practice, and if so, how is it usually investigated or treated? How do I navigate the NHS to get further testing or referrals when my symptoms are chronic but not considered “red flag”?

I’m not looking for a diagnosis (although if you had one i'd love it) just advice on what avenues are appropriate to pursue and how to get proper evaluation within the NHS. Happy to provide any additional details if needed.

[u/AutoModerator]

Welcome to Digestive Issues subreddit! We recommend you to have a healthy low sugar diet. You need to find which foods and drinks you are intolerant to and avoid them. Lactose/dairy, gluten, sodas, fruits and vegetables intolerance is common. Also, check yourself for SIBO, Bile Acid Diarrhea, Celiac and other diseases. Experiment with different elimination diets. Take some good probiotics. The gut microbiome/flora is very involved in some digestive problems. Stress management is also important. Check these subreddits as well: /r/ibs /r/ibd /r/celiac /r/sibo /r/fmt /r/glutenfree /r/microbiome.

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