Horrible itchiness

I’m reaching out for some advice regarding my son. He’s uncircumcised, though I’m not sure if that’s related to the issue, but he has been persistently scratching his groin area. I’ve already taken him to the doctor, had his urine tested, and everything came back normal. We’ve tried switching his underwear type and fabric—boxers, briefs—but nothing has made a difference. His clothes are not tight. He takes a warm bath every night in plain water (no bubble bath), and we’ve been applying diaper cream to help with the itching, but unfortunately, nothing seems to provide relief. I’m feeling a bit at a loss, as he’s in considerable discomfort, constantly scratching and grabbing. Any guidance or suggestions on how to help him would be greatly appreciated. Thank you so much for your time.