4 year old complaining about things touching his penis.

This is a new thing that started about three weeks ago. My 4 year old is complaining about things touching his penis. He wants to be completely naked, he’s constantly pulling on himself, he also complains that the crotch buckle on his car seats (Graco extend2fit, RF and evenflo triumph lx, FF) hurt his penis. The buckle is in the furthest position from his body in both. My husband and I have both checked him, it is definitely not too tight so we aren’t sure what’s going on. He just had his 4 year well child and his pediatrician said there doesn’t appear to be anything wrong with him either. He is starting to do better with potty training but we are in the loose pants/naked phase because he won’t go potty or tell us when he needs to go if he’s wearing a diaper or underwear. He’s not consistent enough with using the potty to go places without a diaper. He has a slight speech delay so communication on the subject is difficult and he usually ends up throwing a tantrum because we can’t seem to resolve this issue.