Hi , My 10 Yr Old Son Just Recovered From

Hi , my 10 yr old son just recovered from pneumonia 2 weeks ago. Went to dr 4 times each time getting worse, and a new antibiotic. He recovered but developed a full body rash now. ( similar to scarlet fever rash pics) slightly raised sandpapery, turns light goose bumpy. No itch. No other symptoms present. Took to dr, didnt find an obvious diagnosis, said viral and to treat with Benadryl. Rash has faded but not disappeared in 3 days, and now his fingers are peeling all skin off. Starts with blistering for no reason. He also said his face burns? Should I push for more conclusion? Any ideas? Thanks so much