TMI - Husbands penis irritated

Embarrassing to even ask but the day after sex my husbands penis became red and irritated. I did a quick google search and found it could be due to a ph imbalance when pregnant or yeast infection.

Has this happened to anyone? Didn't have this in first pregnancy but also didn't have sex this late in pregnancy, I'm 39 weeks. Also is is possible to have a yeast infection w/o knowing it?