My son as red spots around his mouth and on he's bum and have had a fever the last few days?

Rash: Hi Does he have rash on his hands, feet, inside the mouth as well? we are seeing a lot of cases of Hand FOOT and Mouth disease, which caused by a virus. Fever and rash together are likely secondary to viral infection. If the rash is worsening, fever is getting higher then he needs to be seen .

Viral infection: He needs symptomatic treatment---fever control,fluids.watch for dehydration if he has sores in the mouth as well and does not drink well.