What Causes Red Area On Back Of Hand?

I have a red area on the back of my hand. It started out as two small dots this morning and then today it is turned into over half of the back of my hand is a very light red. It doesn't itch it doesn't hurt I don't notice anything except for it being red. It was a really brilliant red this morning when I got out of the gym. And now its a lighter red and its been 8 hours