Two weeks ago, I came home to the US from a trip to South America. A few days later, I noticed some itchy red bumps that looked like bug bites. Over the past week, the small bumps turned into large rashes that merged into one large rash taking up most of my ankle on one leg, plus part of my foot and a bit of my other ankle. The skin turned hard and swollen, and moving my ankle produced small pains in the skin (felt kind of like needles?). I scratched it a little yesterday, and ever since, it's been oozing a clear yellow liquid. There's also a purple bruise forming under the rash. I went to a local clinic, and they gave me a steroid shot, but I'm still worried. When should I go see a dermatologist about this?