Topical medications may not suffice to control psoriatic flares. At this point, I suggest that he may be closely supervised by a dermatologist. Phototherapy may be the management of choice at this point. For severe forms of psoriatic flares that appear unresponsive to topical medications, phototherapy has been employed and showed good results after several sessions.
Was he seen by a doctor recently ?
This sounded like what I had, I had red bumpy warts around my butts, at night it got really itchy i used to scratch myself, take cold shower helped, and I used all kinds of off the counter but it didn't help. Please don't worry, I used to have these warts on my butts, and my doctor gave me Aldara cream 5% (imiquimod) and it went away within two weeks. Aldara is kind of expensive they're $300 for 12 tiny packets of about 4 water droplets. But they worked like miracle.
Please ask you doctor for a prescription.