What Are Blue Spots on My Legs And What is the Remedy?

I'm 16 and Blue Spots Are on my Legs.  Today I was out walking around alot more than usual (7am-12). I came home and my legs were hurting so I looked down and there are blue rings around my ankles and my knees are blue with a few blotches here and there. My legs have been elevated for a bit but they are still a bit blue. PS: I'm 90lb, 5'3" but I eat alot I'm not very active during the summer I had surgery for fibroidadenoma 2 months ago when I was 15