This Might Be Long And I Apologize. About A Month

This might be long and I apologize. About a month ago, I received a rocephin injection. I had been sick recently and had swollen lymph nodes. My doctor offered a shot of rocephin to clear up whatever was ailing me. The day after receiving the shot, my chest turned red and I began to itch. I told my doctor and he told me to use Benadryl. I did this at night as it makes me drowsy and would leave me too tired to function during the day. Fast forward to a couple weeks later, I now had a rash covering my body. It's just pinkish all over my legs, stomach and arms. This was also accompanied by the itching and a low grade fever. I also noticed new spots of petichiae appearing all over my body. I decided to go to urgent care as I read that petichiae is usually not a good sign. They run lab work and told me things appeared normal and said the symptoms I am experiencing are likely not related to the rocephin injection I had received. I also had a chest x Ray that came back clear. I'm a month out from the shot and I still itch l over, I have a rash all over my body and I still have a low grade fever throughout the day. The fever usually doesn't get higher than 99.8. I have random joint pain and occasionally a dull pain under my ribs on my left side.I go to my GP and he says he really isn't sure what's wrong with me and said if it were the injection, we should try prednisone. I did not react well to the prednisone. I was HOT on it and it made my muscles ache. I am really tired of feeling like this and can't seem to get an answer. Could this be related to the rocephin injection? Will it take much longer for the symptoms to subside? I have googled (big mistake) my symptoms and everything from mono to cancer shows up and now I have got myself freaked out. By the way, urgent care physician did a mono (mouth swab) test and it was negative.

Any suggestions?