Okay, taking off mama cloak, donning pediatrician garb (no white coat, kids hate them!!!). I am a pediatrician, though here, mostly mama!
Call a local midwife or birthing house, as most can refer you to a reliable pediatrician or ER facility. Where are you, exactly? I just might be able to help.
I agree witht he past few posters. The location (more in the groin/base of penile shaft) and color/nature of the pus indicates infection. DO NOT ALLOW ANYONE TO RETRACT HIM. Stay right "there", and allow no hands to go near the glans - they're missing the infected area if they concentrate their efforts there anyway! Offer to hold his penis for them as they do their exam . . . this might help DS be more comfortable - no hands more gentle than mama's hands.
Don't wait until tomorrow. If no friends/relatives in the area can help by referring you to a ped they know (for example, we see friends/relatives children if they are sick while in our neighborhood), call the local Children's hospital ER (not just any ER that happens to see kids. . one affiliated with a pediatric surgeon (probably more helpful in your situation than a urologist as this seems more of a skin issue that happens to be located on his penis), then go to the ER.
Go tonight mama. Infection can spread quickly and that's nothing to wait on.
Sending good thoughts for you and DS.