I had chest pain and difficulty breathing after taking ecstasy. I also was smoking weed during the week and after taking the pills. What caused this?

Why to say "No!" Your dealer does not sell FDA approved drugs. Who knows what garbage and potential poisons are in this junk.? Maybe the pot was grown with a bunch of pesticides or your pills had toxins added. There is a reason that these drugs are illegal! Stop drug abuse. If you can't, or you don't care if they kill you, get treatment. You are a better person sober & will have a safer, often happier, life.