Phase Question

My mom seems to have entered a new phase where she’s CONSTANTLY talking to herself in the mirror or in her bed…thinking herself to be a child and that the person in the mirror is a childhood friend. She thinks people are there that are not and always thinks someone’s coming to pick her up. She’s very restless and constantly walking back and forth to the bathroom and talking to people who aren’t there and moving things around. I’m wondering if this is just another phase or if it’s a rapid decline indicative of the end coming soon? Would love to hear from anyone who has experienced this change. She is 67 and has been officially diagnosed for 3 years (although had symptoms for at least 2 years prior to that).