Hello, My Son Is 22 Months Old And After Coming

Hello, my son is 22 months old and after coming back from a park he got a rash on the both of his feet and no where else. He has g6pd and I would like to know if he can use Benadryl itch stopping cream. The active ingredients in it is Diphenhydramine hydrochloride 2% .....topical analgesic and zinc acetate .1% .....skin protection. The rash isn't really bad so I just wanna know if it's something I can use if it gets worse just for temporary relief so he's not just trying to scratch himself so much. Thank you for your help