Welcome @curiouskitty, Like all of our treatments, Keytruda does come with its list of potential side effects. I'm sure your doctors and nurses have gone over those. Any change like you described would be concerning to me too. The immunotherapies can be lifesaving, but they also have serious risks, such as Pneumonitis, an inflammation of the lung tissues. I'm not a doctor, or clinician, and don't give medical advice. If I were in your shoes, I would reach out to my team. Have you reached out to your oncologist?
It's great to hear that you are stage IV and still playing pickleball. Me too! I play just once a week with a group of friends, so we're very understanding of each other's limitations and ailments. We laugh a lot so it's great therapy in many ways.