How Can Severe Pain Joint Pain Due To Chikungunya Be Treated?

Hello Doctor, My father, age 61, was diagnosed with Chikungunya in mid September. He had fever, rash and joint pain (hands and feet) for a week and subsided later on. He has diabetes and high BP, for which he takes daily medication. Now, after in early Oct his joint pain re-emerged and now he has severe pain in hands, feet, shoulder and back with severe swelling in hands and feet. It has been over 2.5 months and still no sign of relief. Consulted many doctors (PCP and RA expert) but no relief. Please help!