Skin rash/boils

Ti

I have a friend with a 9month old who has been using cloth diapers intermittently but more so now. In the last month or two her baby girl gets welts/boils around her labia when wearing cloth pocket diapers. No issues with disposables. My friend stripped the diapers recently and there is still an issue. When her baby was a newborn she used covers with prefolds and didnt have an issue. Any ideas?