Is this exzema or heat rash? pllleaseee help...?

my daughter is almost 7 weeks old. shes got small rashy looking spots on her upper body around her chest, a little on her back and a bit on her face around her jaw line. i had our 6 week check with gp monday just gone and she said its normal due to hot weather we having lately, ive just had our 6week check with our HV and she said its exzema? her daddy does have asthma amd there are family members with exzema and asthma. who do you think is right? i dont want her to suffer with exzema, im worried plz help xx