If absolutely nothing "else" changed.... he needs to go see he doctor.
Over 20 years of smelling and tasting the same... and then a sudden change in 3 weeks is probably a sign of something being wrong. The two that leap to mind are infection or diabetes. Mens hormones cycle every day, and stay that way from puberty until near death. They're pretty stable. If HIS hormones are off, well, it's pretty rare. I would really think; infection or diabetes off the cuff. ASSUMING none of the below have changed
Changes that nix the drs appt:
- medication (including vitamins and other OTC meds)
- diet NOT ONLY WHAT he's eating... but what he's not. Ketosis has a very distinct smell. As do several other biological responses to diet. Dairy, for example most westerners cannot smell, but to asians... people walk around smelling like sour milk
- drink changes (coffee, no coffee, soda no soda, water no water, etc.)
- dehydration (dehydration smells awful)
- exercise
- starting smoking
- quitting smoking
- sour laundry (really, the smell gets into our skin, and after a few days doesn't scrub off for *some* time)
- etc.