I am not a peds nurse and of course you need to see your doctor. But, all 5 of my children get 5ths disease every year. It is a fairly harmless rash that starts at the upper body then spreads downward to the lower extremity ( or this is the way it happens with my kids). My kids get a fever and just dont feel well. This is caused my the parvo virus and they dont give treatment for it, since it is a virus. I have been expecting our yearly round for weeks now. Last year my daughter had it so bad her body looked like a map. Please see your ped doc they can do a test for this, a parvo titer.... I hope your baby gets better