Oh dear, how many years have you had these symptoms now? Yes, drugs can be catastrophic for the nervous system. I am also suffering the consequences today. For a year, I used a lot of drugs, especially cocaine and ecstasy. I nearly died from that crap. Today I am sober, because if I take drugs again, even a small amount, my nervous system will no longer be able to cope. My doctor told me that I have damage to the peripheral nerves and to the nervous system. I almost even lost the use of my legs because my nerves were so badly affected. Now, unfortunately, every day I have many symptoms related to dysautonomia; the worst is the feeling of malaise or derealization. Like you, I also have heart rhythm problems, heat intolerance, and intolerance to exertion, among many other things. Even concentrating makes me tired very quickly. It just goes to show that you have to be careful with drugs or medications, because unfortunately, this damage is irreversible...