What Causes Red Spot On The Leg With Stinging Pain?

Whilst walking in a wooded area I fell and felt a stinging in two places on my leg. The sting was quite painful but eased a little after a few minutes but did not disappear. About an hour later I checked the area and saw several white raised patches about 1 to 2 cms in size. I then started to develop pins and needles in my leg which felt like someone was pressing tiny needles against my skin, all over my leg. The following day the sensation was less and I checked the My leg again. It now showed a single red/brown mark about the sixe of three pinheads and round it were 3 half circles radiating from it. I still had tingling sensation but not as strong as the first day. Later I checked again and there is still the dark spot but now a dark wide circle around it. Have you any idea what this could be and should I seek medical advise or just ignore it.. YYYY@YYYY