Suggest Treatment For Pituitary Tumor

My brother was diagnosed with a pituitary tumor and acromegaly. His tumor was removed in August. Following the operation, he could sleep without his machine (for Sleep Apnea) and was feeling well. After about a month, his skull returned to its normal size. He also had to return to using his breathing machine, had difficulty swallowing, started having sever headaches that resolve with how he positions his head on a pillow, and has debilitation pain throughout his body, especially his joints in spite of the cortisone shots he is receiving for osteoarthritis. Could he also have a Chiari malformation as a result of the change in the size of his skull after surgery?