Hello, 
Body rash over two months is a clear indication of infection (fungal, bacterial, parasitic, viral), allergy or exposure to some irritant that your body is sensitive to.
Other factors causing rash are 
Psoriasis, hives, contact/seborrheic 
dermatitis. You are suggested to visit a 
dermatologist & get physically examined.
In the meantime avoid sharing your toiletries. Use corticosteroid creams or 
aloe vera based creams to apply locally. Oral 
corticosteroids are effective. Take vitamin D supplements or vitamin D rich food. 
Antihistamines, antibiotics & anti-inflammatory medications are effective. Apply cool-wet compress & do not take any food that triggers the symptoms.
Avoid sex while you are being treated & stay away from addictions if any. Take regular showers. Always apply a medicated moisturizer or corticosteroid based cream after bath. Do not leave the skin dry.
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. Nupur K, General & Family Physician