2yrs ago I had lobectomy for a stage 1 tiny spot that was biopsied. Dr said I didnt need oncologist because they got the cancer out clean. 9 months ago I was being treated for sciatica. After 6 months of orthopedist an mri showed cancer on my glute muscles. Stage 4. Pet showed some tiny spots on my lung and one lymph node involved. Radiation took the pain and swelling away. Now getting keytruda. I’ve had 3 infusions. My rump hurts now and I want a scan to see what’s happening. Dr says not to worry, that sometimes during immunotherapy the cancer can grow. How soon after starting keytruda should I expect a scan?