I have been having pain in my right hand and some in my arm for a week. I went to the doctor and got a pain shot and a steroid shot for possible carpal tunnel. The next day I was driving and suddenly felt heat in my upper right arm about 4-5 inches below shoulder and about 3-4 inches wide. It was red and felt hot to touch. It last for about 6 hours before it went away. I haven't noticed any swelling or any other signs besides some slight aching in my arm and shoulder. But like I said I was already having some pain in my arm before. I have a horrible problem with anxiety and am worried it is/was a blood clot. My fiance thinks it may be a symptom of the steroid shot from the day before.