Once upon a time, a long long time ago when I did this kind of stuff, I dropped some molly at a club, I took the regular dose i.e. 2 at once but I guess it was really pure shit. Hit me like a TON of bricks, basically I was tripping balls. I started hallucinating thinking everyone was looking at me and talking about me. I walked around the club paranoid, then I walked out and through the cops and security were coming after me with helicopters and those big ass lights.
I called a cab and sat on the sidewalk thinking oh shit. Went home and slept for like 2 days. I was paranoid after that for a few months, took some time to rub it all off!
I would go to raves and pop 10 pills a night, it was just crazy shit back then. I can't believe what I was doing.
My only advice, just watch what you're doing. You're not going to stop just because someone tells you to, just be responsible and know when to ask for help!