What To Do For Rashes, Swelling In Arms After Taking Clindamycin HCL And Hydrocodone?

Hi, so i my surgen perscribed me Clindamycin HCL for my cavity infection and hydrocodone 7.5-325 for the pain it s been causing. i started taking this medicine about 3-4 days ago. the only side effect I ve noticed and that it s concerning me is the day after i started taking that medicine, i noticed a small rash on my arm that kind of looked and felt like a few mosquito bites close together but then the next day i realized the rash was getting bigger and not only that but that part of the arm started swelling. now on day 4, that part of my arm is super swollen. a litte scary.