My 17-yr Old Daughter Just Got Back From Running For

My 17-yr old daughter just got back from running for track and her mid-back is very itchy and of course she's scratching it, so therefore its causing redness and small and big welts all over. Temperature outside is 65 degrees so not sure what's causing this?

If there is a charge for this, please do not answer, i am not willing to pay for a simple question.