Has anyone had arthritic pain after treatment with Keytruda?

Late in April 2024, I was diagnosed with adenocarcenoma of the head of my pancreas. I had two infusions with Fulfironox before my genetic testing confirmed the cancer is related to my MSH 2 and MSI Highsnd a candidate for immunotherapy, Keytruda. Five infusions of Keytruda later, I was deemed to have had a complete response, but after treatment four I had begun experiencing hip and knee joint pain. After the 5th treatment, I became so “locked up” my husband took me to the ER. After the ER doc finally consulted with my oncologist, I was prescribed prednisone ( a shot in the ER) and a MedPak. This worked well, and a later visit with the oncologist resulted in a prescription for 10 mg per day. However, all my medical team members wanted me to reduce my dependence on the steroid. I very slowly weaned myself off but stiffness had returned and my hands are very swollen now. I read that many Keytruda users have experienced some pain post-treatment for three to six months. I am at four months. I am now going to PT and go to SilverSneakers exercise program twice a week. Any advice or suggestions from fellow survivors?