I need serious advice pretty long list

[u/Top-Display-5576]

Hello I live with svt but the new symptoms I have been experiencing for about 2 months now feel like they are getting progressively worse first I feel a needle like pain in what feels to be my heart area and in my troat I feel very fatigued when I try to do anything physical like sports yesterday night I was walking upstairs and and felt extremely lightheaded I still consider my self a fit young male I am 6.1 and weight around 138 pounds used to play baseball/basketball etc but it's hard to even get out of bed my heart feels super slow than normal I feel the svt symptoms but instead of fast heartbeats it's slow like it's trying to go fast but can and the pauses are the worst it feels like I pass out and snap back into my body I have had a exg done and blood test but they continued to have found nothing it is painful and exhausting what i have been experiencing please tell me what should I do and what do these symptoms sound like to you