I m 33 Male, 190 lbs Caucasian. This past Sunday I quit using Synthetic Marijuana, after about 1 month of continuous use. I had some minor withdrawal symptoms the first few days (Restlessness, lack of body temperature control, no appetite ). Those have ceased at this point, but I am still coughing a lot and I have a sharp pain beneath my left shoulder blade when I do cough. The coughing results sometimes in a mouthful of foamy mucus , but no real phlegm or coloration to the mucus. Should I be concerned about this coughing? I expected some issues as obviously smoking irritates the lungs ect, but I don t understand the coughing if I am not coughing anything up... Thanks, Aaron