My Husband Is 71 Years Old And Has Been In

My husband is 71 years old and has been in exceptionally good health except for Prostate CA in 2004. He had it removed with no other additional treatments. He sees a primary care doctor once a year for a well check. Recently he has begun to experience dizzy spells. Mainly when he wakes up in the morning. He has had an ache at the base of the skull as well. He does wear a CPAP machine and for some reason he feels that it might be connected somehow with that. It has become bothersome more and more in the last few weeks.