I guess it have something to do with the blood pressure. When you're active your blood flows faster, and the vains get wider. It often bleeds.
When the temperature outside is high, the same thing will happend.
That the spots dissapeared... Hmm I guess it's because the bloodpressure is lower because she've rested and slept.
(Sorry for the bad grammar)
If you're really going for something, you can't fail!