Thanks for your query.Based on the facts that you have posted it appears that your boyfriend has developed what is called as Mucocutaneous Candidiasis
Please get his blood sugar levels test done to rule Diabetes
as this is common in diabetic persons.
Please ask him to take anti fungal medication
orally along with anti fungal jelly like Fluconozole for local application over affected area.
Get the prescription from your family Dr.
Observe proper personal hygiene by cleaning the genitals with warm water twice daily.
Do not attempt sexual intercourse till it gets cured completely.