what are the symptoms of dementia?

My Mother has dementia and has had it for about six years. We've moved her into our house and have provided great care for her. In the last few days she hasn't been telling us when she needs to have a bowel movement, and has started to go in her Depends pull-up pants. Is this a normal progression with the dementia, and what can I do? Is it time to move her into a nursing home (which she can't afford and it will be through Medicare.) She is 90 years old and is in excellent health except for the dementia. She has been incontinent with urine for a long time already and Depends has been the answer for that, but I can't take the poop clean up!!! Help!