Suggest Medicines For Red Welts On The Upper Thigh

I just recently had some red welts show up on my upper right thigh. It looks exactly like a cat paw print. Larger welt in the middle and 4 smaller welts around the bottom of the larger welt. I did not know they were there until I was putting on a pair of shorts and i felt my leg was really warm in that area. I put a forehead thermometer up to it and it showed 100 degrees. I didnt know if that would even read right though. It does not itch, and there are no pussy pockets. It is just red and and feels hard like a mosquito bite would. I dont remember anything biting me, or any injury to that area. I have been putting rubbing alchohal on it. It is not getting any better or any worse. It does not even hurt. What do you think it may be?