How Can Itching And Swelling On The Shoulder Be Treated?

After being outside all day, I found that something had bit me on the shoulder, could have been a mosquito, usually after a mosquito bite I swell up and itch for a few days, but after a few days I got a rash that spread to my shoulder and up my neck. I tried Hydro-cortisone cream (which seemed to make it worse), Benedryl gel , alcohol, witch hazel, but nothing is stopping the itching or the rash. There are ticks where I was, but I did not see a tick that night and I have not seen a bulls-eye where the bite was. What could it be and what can I do about the itching.