my aging mom

ok guys...I have a problem here. My mom...she is only 78 but in very poor health. She only weighs 65 pounds and has osteoperosis(sp) and emphazima. She is on oxygen and also has an inhaler.
I have never been very close to her but as she has gotten older and had her health issues, I do try to be there for her. She is after all, my mother. Because she does not get out and about at all, she is very needy and has taken to calling me often....very often and while her calls are a pain in the butt and her conversations boring...I have to say that she has alway been very coherent and aware. She is in alot of pain with her back. Recently I got her on a percacet (sp) patch for her pain. It seemed to be working fine. She was having trouble swallowing pills and they were taking her appetite and causing other side affects that the patch did not. Because of her size, the patch over a period of a couple of weeks began to affect her sleep...also my brother discovered she was not taking it correctly. We had her stop the patch and just last week she was given an epidural for her back pain. Oh she is in no pain now but is so incoherent it isn't funny. I left her house in tears today. she thought I should hang up the phone because our conversation had ended. I tried to call her yesterday and she just kept repeating my name over and over and then would hang up. some have told me it is dimentia or alzheimers setting in...i really question this...this is all new to me. Has anyone any thoughts, ideas, experiences in this? Because we have not been close, I did not expect to feel this way. I want my annoying mom back...at least she made some sense! My neice stopped by to play a game of cards with her...a game she's always played and loves...it was just sad, my niece handled it well but broke down crying when she left.My brothers and I have always promised her that she will not be put in a nursing home...her biggest fear.