I caught a cold from my toddler as both colds and hand foot and mouth are circulating at her school. I was sneezing, fever, runny nose, raw throat and a sore on my lip. Towards the end of my cold I got a flu shot given at the hospital I work at. THat evening when I went to bed I noted the backs of my knees were sore. When I woke up the next day and for 4 days now since I have had a sunburn like in appearance and burning feel rash behind my knees and to a milder extent the bends of my arms. I have never had any symptoms other than maybe generalized malaise after flu vaccination. Last year I got the flu shot while being treated for bronchitis and was fine. Could this be dermatitis from a reaction to the flu vaccine? How long do these rashes take to resolve?