I took .5mg of MDMA last night and I stopped feeling the intensity after about 10 hours. However, just as I started to feel it wearing off, I developed a tight, achy feeling in the center of my chest . I do not know if it is heartburn , a lung infection, or something else. It has been well over 12 hours and I still have it, it worsens when I bend over and feels sharp when I inhale deeply. I can breath normally and do not feel congested, but I am concerned because I have never had chest pains before. I am a 20 year old female, 5 5 and 135 lbs.