Need help for unexpectedly fussy eater

My DH has moderate Alzheimer’s and has recently become unexpectedly fussy about foods he has liked in the past. This happens most often at breakfast, and I feel like I play a guessing game many mornings. For years he had granola with yogurt and fruit … and then about a month ago he rejected it, so I moved to just yogurt and fruit, because it was the “chunks” in the granola that bothered him. After several weeks of that, he decided he didn’t like the yogurt. Just to experiment, I gave him the granola and fruit again with a little yogurt mixed in, and he ate that for about a week, and then today he rejected the granola again - it was the chunks again. I’m happy to make him anything that is satisfying and healthy — I just can’t figure out what that might be. (He does not like eggs or cottage cheese, and my concern is for him to get enough protein.). I know that personal tastes can vary greatly - but am wondering if anyone has had a similar experience and found solutions. Thank you!