marshmallow + skin thing

Marshmallow had redness on his belly for 2 weeks, I thought it was just the heat. Then he start licking the same spot every night. The vet said it is allergy, maybe to the floor cleaner I used. I change to plain water and vinegar, and now he is much better. They gave cream for 7 days and antihistamine, he hate the taste of the cream. I have to put it on his belly while he lie on my lap and watch Netflix. He is a good boy but he really hate that. Blood test was normal, so not so serious. Still, I check his belly every day now. Feel bad that I didnt notice earlier.