Uncircumcised

My son is almost 4 and uncircumcised. I just started potty training about two weeks ago. But he’s saying his penis hurts. The tip is a little red but he won’t let me touch to see what’s wrong. He’s crying and I notice he hasn’t peed today. When I sit him on the toilet he cries and says it hurts and wants up. ??? What should I do? I’m worried

Liked I’ve noticed he plays with it and I tell him to stop. Could he be getting dirt and germs in it?? I read not to pull the skin back to clean it until their around 5