Dazzee,You may have drug induced Psychosis. Taking a drug like LSD at that young of an age could have done a lot of damage to your developing brain. Even long term use of Pot in the vary young can create problems down the line. I did some drugs like Acid and Mushrooms in my early 20's smoked Pot and other things. Smoked opium a couple of times when I was in Viet Nam. I was lucky because I don't have an additive personality. I never over did it. I have many friends from that era who are either dead or now permenitly waisted. I never had problems with flashbacks or nightmares due to drug use. I do feel the drugs may have help trigger my depression.
You need to see Psychiatrist who has a lot of experience with how drugs effect the brian and what the best treatments for those effects.