What Causes Redness And Pain In The Thigh Area With Tiny Bumps?

Yes I have a red area on my thigh and its about the size of a quarter and there are little tiny bumps inside the red area that have a yellowish clear fluid in them. It itches and hurts. It is something I had twice and went away and is back again. The first time I was told it was a spider bite but that was months ago and it went away and has come back twice. Please help!