My father in law seems to be progressing in his dementia! Do I have cause for concern and what is next?

Today, for the first time, FIL could not remember my name. I have been with him practically 24/7 in his home every day for the last 3 years. He has lost interest in keeping himself up. Teeth, drinking water, motivation to exercise. He wakes, has breakfast and promptly falls asleep. If I can get him to walk or pedal he then falls asleep. He eats lunch, falls asleep. He is constantly dozing. This is a new behavior. I feel like he's kinda given up. He's moving excessively slow, about twice as slow as before.

He cannot make decisions for himself but that is not new. He's super codependent and my husband and I have him decide what he would like to eat, wear, etc. his deceased wife always made those decisions for him and I think it was initially freeing for him to be able to think for himself but alas the reality of choices mixed with his confusion he's pining for the days when MIL told him when to go to the bathroom along with every other decision for the 47 years of their marriage. Hence the giving up.

Am I reading too much into this all or are big changes coming sooner than later?