What Causes Excessive Sweating In Underarms?

Dont know if you can help but its worth a try. I have been a heroin addict for 2 years and i have been sober for just over a month. I feel good and all but im sweating really bad from under my arms. i have to change my shirt 4 to 6 times a day its bad. is it from the heroin or is there something wrong? Thanks for the help.