Hi, thanks for using healthcare magic
Allergies can be provoked by dust mites, environmental allergens like pollen or animal fur, foods, medications , chemicals, mold.
If you have not altered his diet , detergent, soaps or creams then it is likely that if there is something new in his environment that it is the reason for the rash
If it is the carpet it would be the dust in the carpet or its fibers. If it is the dust and the landlord is unwilling to remove it then it would have to be regularly cleaned each day. IF it is the fiber that would be difficult.
YOu can consider allergy
testing to determine what specifically is causing his reaction. This can be done as a blood test
or skin testing.
I hope this helps