Is this depression or start of dementia?

I went to my mom's over the 4th (3+ hours away by car). My brother, who lives locally, was sick again. I'm not certain he was really sick, probably more burned out. Mom has been having issues with her back (finally diagnosed as sciatica) since March. She had been to the dr the day before, then her back issues started the next day. Dr prescribed some "narcotic" which she took for 1 day before saying it made her sick. I told her to call dr's office back and get something else. Nurse told her to eat a full meal before taking again. She refused and never took another pill. Mom had us on a goose chase for every product sold online and in stores for sciatica. Nothing has helped. I did get her a fancy rollator, because she was sort of using a cane and bending way over to hold on to furniture as she made her way around her home. Finally, she went to the dr about 2 wks ago. She was all happy, then read the prescription warning list (a separate page). Refused to take it. I asked why she didn't call the office and say she wasn't comfortable taking it, ask for something different. Not going to do it. She said she thinks the dr wants her to take more pills because she only has one prescription for high blood pressure - somehow he's evil and wants her to take more pills. And every little thing he did was wrong. He said if this did not work, he'd send her to a specialist. She'd asked about the "shot" women get while giving birth. He said oh yeah, the specialist would do it. Her friend, who's grandson is in the medical field had told his grandma oh that's serious. Yeah it is, as they inject it in your spine. My mom said well her dr acted like no big deal (he's evil). So this weekend, she's in a foul mood again. I asked some simple questions like what did she need done, and was told if I had to ask I was stupid. So I did laundry, made beds, put winter linens away (when asked where were the sheets she wanted on the beds - response was I DO NOT KNOW - with crying). Then she got up and found one set. I went to the grocery for her. Then she says oh I want the rose bushes trimmed and those weeds pulled - to which I said, didn't you just have the landscape guy out here Thursday (for his pre visit before the job). This guy does a thorough job. She said it looks awful and I don't know when he'll be out. I did lose it as my own flower beds are in horrible shape. I said, well that's nice, I have to do your clean up - when he's coming out - probably next week, and mine is a lot worse. Cue more tears, plus guilt trip (if you can't do that much for me...). So I did the yard work and more (which she later criticized). She then asked me to feel her knee as she moved it. She had a slight knee problem a year or so ago; specialist did cortisone injection and it was all better. Her doc said oh we do those here. When she asked for another shot a last year (fall), her doc said no. She now is blaming the lack of a shot on her back issues. Her back now doesn't hurt as bad as her knee - it "clicks". I said yeah I feel your joint. OH I CAN'T HAVE ANYTHING WRONG WITH MEEEEE (tears). I said I'm not a doctor, I wouldn't know if it was good or bad - what do you want me to do? Just tears and how I was stupid, and I should leave. I got my stuff together then she said if you leave, never come back. It was a circular argument. I did everything she wanted, but then she'd add something else spur of the moment, or right when I was in the middle of something. During dinner, she kept having me get up and get something or do something else, then laughed. I said it's really not that funny (cue tears). She decided at the 11th hour that some sweaters had to be folded and put into her closet (a walk in closet that can barely be walked into). I put the items away and said this closet needs reorganized. Ka-boom. She's even told me that before. Every word I said, even comments that were innocent enough caused her to lose it. I had said she needed to go see a doctor or get another doctor. Not gonna do it. She's been on a kick that she wants to live with me. I told her a visit would be ok, but not permanent as we are oil and water. Now, I've rejected her. Everyone has rejected her. She talks about how she was wronged by her parents (this is well over 75 years ago). My dad died when I was a kid, so she feels I owe her because she had to be a single parent. She did so much, which really, she did provide financial support, but not a lot of emotional support. She's now spending a lot of time sitting in her easy chair, then complaining she's bored. Another source of conflict is her hearing - which is bad. She keeps saying it's just ringing in my ears and won't get it checked out. My brother and I are not close, and he's one to steer clear. He goes to mom's a couple of times a week, living about 2 miles away. He'll do errands, but not much around her home. She will not go to AL or NH. Help.