Hi and welcome to HCM.
It seems like his skin is irritated because of too much substances applying on it. If all these werent helpful he should do swab test you too, it might be STD
and exact cause should be treated by systemic antibiotics. Also some other dermatologic diseases should be considered. But I suggest to go step by step and not ot have sexual intercourse till it heals. There shouldnt be pus underneath foreskin,there might be smegma
,it should be easily cleaned out. Wish you good health.