Daughter might have a Heat rash?

But im not exactly sure, we didn't really have her outside for very long yesterday, we mostly kept her inside. she's 7 months, almost 8.And she has lots of red blotchy spots all over her back.Shes been very sleepy since yesterday, and it also looks just a tad bit worse than it did before. Any help? Also, any one who acts like a smart *** or wants to make immature comments, i rather you don't but if you do i honestly can care less.