Iche symptoms and conditions

I started taking sulfameth/trimethoprim for my acne nearly two weeks ago twice a day. Two days ago I started feeling what I thought were growing pains in both my legs. The pain slowly made its way both down and back up the legs. The next day I looked down at noon and these red dots had appeared all over my body. I've had a loss of appetite and the red dots have a mild iche to them. I also had a very very bad migrane for the rest of that day. Today I woke up and I am complety covered in red dots. My face is red, but not really dots, it feels more like a mild sunburn.