I Got A Rocephin Injection And The Next Day Had

I got a Rocephin injection and the next day had a strange reaction...whelp like red areas came up on my left forearm...my knees have a splotchy red areas...just on the kneecap area...and now my lower legs are starting the same...some of the areas are tender and sore....a couple of them itch on my forearm....weird huh? No shortness of breath or mouth swelling....but my teeth top and bottom...actually hurt. Got the injection for a sinus / ear infection