I Ran A 5K On Saturday, But I Haven't Run

I ran a 5K on Saturday, but I haven't run since. I've got these weird spots of swelling on my shins, on the inside of both of my legs up at the top, under my knees. At first I thought it was just muscle (wishful thinking), but I think it's too far toward the front for that. It's squishy, like it's filled with fluid, but it doesn't hurt at all.