Lasting heart palpatations after stimulant misuse

[forum_user123]

For the past 2 years I've had an issue with strong and persisting heart palpitations. It occurred after misuse of an unprescribed stimulant drug (modafinil) for about a week or two. As soon as issues appeared I ceased use immediately. Main issues are a persistent strong pounding and occasional minor chest pain. I'm a male in my early twenties, no family medical issues, have gone to a GP and gotten blood pressure checked, EKG and blood tests done, no prior physical or mental health issues. The palpitations present as my heart beating very strongly, while everything else feels normal (heart rate, etc). The palpitations are exacerbated strongly by exercise and eating. Approximately 20 minutes after eating a meal the symptom gets worse, peaks maybe another 20 minutes later and slowly goes away after an hour or two. Alternatively, If I don't eat enough in a day it also gets much worse in which case eating a small meal usually improves it. How I've been eating recently is by far the strongest factor in how strong the palpitations are. Stressful activities (e.g. fighting other players in an online video game), or standing up very quickly produces proportionally very strong palpitations for a short time, especially if I've just eaten. Doesn't make a significant difference what kind of food I eat. The palpitations don't coincide with anxiety, I usually feel relatively calm albeit slightly physically uncomfortable when it gets worse as I've gotten used to it. The symptom is weakest when I wake up, but still noticeable. During this period i haven't taken medication, no caffeine, alcohol, etc. Was always a pretty chill and anxiety free guy before this.

For the first few months I had other symptoms, including:
- Paranoia, that was absent in the morning but would build up after I woke up before peaking maybe 15 hours later with very shaky legs and jaw, after which point I would abruptly feel very sleepy. This was everyday like clockwork. It wasn't panic but rather a droning anxiety that lasted for many hours, and I was entirely concerned about strange things such as reality breaking down or people on the street being demons, even though I knew it was complete nonsense. Never experienced those kinds of thoughts ever before, it felt surreal. If I managed to go to sleep before the paranoia peaked, in the night I would always be woken up out of my sleep and experience the shaking and strong wakefulness but strangely didn't feel the paranoia nearly as much.
- Frequent hypnic jerks (very sudden jolts of stress that would last a second or two), always multiple times when falling asleep and sometimes while wide awake out of nowhere.
- Increase in libido and and almost persistent contraction of the testes.
- On a few occasions shortly after sex I felt a noticeable shortness of breath for 10-15 minutes, but no other symptoms present or changing with it, no anxiety, no worsened palpitations, etc.

These symptoms slowly decreased in magnitude over the course of a six months. The heart palpitations also reduced in magnitude but are still very present. The other above mentioned symptoms have come back somewhat temporarily when I've missed a nights sleep on a few occasions.

Spoken to a GP but given that there is nothing diagnostically wrong with me so far I can't really get any more advice, might be that I'm terrible at communicating face to face. What I did was stupid and reckless and I regret it very much. Any advice on how to seek treatment is greatly appreciated.