How to get rid of the ichy red rashes.

Had fever on Saturday taken nischipcold for that, again got little temp on Monday taken nischipcold for that, bt due to little cold my nose was blocking si taken the otrivin nasal drop which tasted some wired then usual, so washed it off, then from Tuesday morning saw the red rashes in my hands, legs. Wednesday went to a doc he diagnosed as this rashes are from fever, as my face was also slowlen, I feel my hands are jamed unable to fold properly, joints are paining, so he has given a steroid injection named HYDROCORTISONE, after that I'm feeling like it didn't worked the red rashes are more visible. He even prescribed with some more steroid tablets, please guide me what I should do, to get rid of the red rashes and the itching as it's itching very badly.