Sorry to hear about your father's condition. What therapy is he receiving for both the cancers?
Pain in the pelvic area can range from a harmless condition to metastasis in that area. With the background of cancer, it is better to get metastasis ruled out by doing a abdominal CT scan
I am sure the neurologist
will also order a CT/MRI
of the brain, which is going to rule out brain mets as well.
It is important to support him at this stage because he is suffering from a lot of problems. Hope he gets well soon.