Yes, Please. My Husband Is 61, In Good Health Except

Yes, please. My husband is 61, in good health except for high bloodpressure which is controlled by medication, but he has started lately having something like hot flashes at night, when he goes to bed. We live in the greater Houston area and it is hot here, but when I'm comfortable, he's sweating and his pillow is drenched in no time. This has only been going on for a few weeks. He went to our internist who did blood work and says everything is normal, but we know it's not normal. Any ideas about a specialist or source of information about this?