What are these changes in my husband? Any experience?

A couple of days ago my husband changed, although subtle. When he got up in the morning I found that he had slowed down in his mind by half. He has vascular dementia and almost total memory loss except for close family. He still seems intelligent. Now he is extremely distracted by anything, including his own thoughts. It takes him at least an hour and a half to eat a meal. His response is slower when you ask him something. Have others experienced this? On a separate problem he seems to be having trouble swallowing, almost like his swallowing reflex is effected and he is burping a lot. What is going on? Thank you for your help.