has anyone been having issues with heat rash on your babies this summer? mine had a rash, took a…

has anyone been having issues with heat rash on your babies this summer? mine had a rash, took a while to go away and now it's back again... besides keeping him dry and not putting lotion on it, is there anything else I should/should not be doing? he's a sweaty 7 month old... it's starting to spread to his face too