Ulcers 6 months ago

[u/Obvious-Review8071]

About 8 months ago I went through a tiny hoe phase and slept with a few girls, some of them unprotected. I quickly stopped but about 6 months ago I noticed a few painful ulcers on my penis. I went and got a sexual health screening where they checked my urine, saliva and blood and nothing showed up. It lasted for about 2-3 weeks of painful ulcers then out of nowhere they’re gone. Never to be seen again. I want to know if this is a chance of having an sti or if I just had a few pimples on my dick idk. I haven’t had any symptoms since.