this has been happening to me. I had LSD when I was 18 (iv had it since then) but that was a really bad trip. im now 23 and i keep having kind of like flash backs when i get stonned I feel like how i did when i was on LSD i keep having a really powerful paranoia feeling, I see things which arnt their like the walls start to move and wobble like being on lsd and recently when I havnt been stooned I feel like its affecting me when Im sober, I keep having strange thoughts that I died or im in a coma some were diying and sometimes i feel like the only way to wake up or to find out 'the truth' whatever that is is to kill myself. It seems really plausable when I feel like this its really scairy.