Purplish spots on skin and hair loss

Question
I have recently discovered purplish spots on my rats skin and he has lost a lot of fur. I haven't seen him scratching himself, I thought it might have been just a bite from my female rat who recently had his babies. He had scabs but they aren't there anymore. We have this anti-biotic called tetracycline, would that be ok to give him? The symptoms from him are starting to appear on my female I am really worried.

Answer
I'm guessing this is stemming from an ectoparasite - have you tested or treated him for parasites lately? and no, you shouldn't start him on tetracycline without knowing what is going on. I suggest you see a vet or take him to someone who REALLY knows rats to double-check any assumption you may have, and go from there. Ideally, a vet; as they can prescribe proper medications depending on what it is.