Sorry for the long post in advance

Some background before I get into the main issue...
My mom will be 70 this year. She has 6 children and I'm the youngest (35 yr old). She has always been a home body when I was growing up, but she always went to our events like plays, ball games, etc. She really enjoyed staying at home though. She was never lazy and always kept the house spotless and made dinners, etc.

Once we moved out of the house, she was still a home body of course, but went on a vacation at least once a year. Once I had children, she would also continue to go to their events like she did when I was a kid and was always wanting us to come visit.

Stresses in her life...
My dad was killed in the coal mines in 1985 and I was 1 years old. So that is when the big stresses started. She has always been on some kind of medication for stress/anxiety as far back as i can remember which probably stems from dad being killed.

Throughout my entire life, 2 of my siblings has always caused a lot of stress on my mother due to drugs. One is mid 40s now and the other is 50. They have never grew up and my mom has always been forced to focus attention on them because they were always needing a place to live or always needing money to be bailed out of a situation. Now she is not only dealing with them, but there children are also following in the drug footsteps of the parents and Mom has to constantly deal with them living with her, among other things.

The personality change...
My mom ended up having a mini stroke in 2014, but a year or 2 prior to that things started to change slightly. She slowly stopped coming to visit us and slowly stopped coming to my children's events. This was around the time when one of my siblings had to come live with her again. About 6 months after my sibling left, my mom ended up randomly blacking out in the dining room. It was determined later that she had a mini stroke.

From 2014 until sometime last year, she was constantly having dizzy spells and her blood pressure would go way up whenever she stood up sometimes. The doctors thinks that she has Postural orthostatic tachycardia syndrome (POTS). Starting last year she didn't complain about dizzy spells anymore and now she constantly complains that she can't eat without getting nauseous...but she never throws up. The doctors say she has gastroparesis now.

From the time she had the stroke, she completely stopped going places. No more vacations, no more visiting us, nothing. Her excuse was always that she was afraid she would have a "dizzy spell". My son couldn't even stay the night with her because of her "dizzy spells" even though my step dad was there. We also never feel welcome when we come to her house anymore. Since last year, the excuse is no longer "dizzy spells", now it's nausea. Whenever we talk to her on the phone, she is always negative about everything and makes everything selfishly about herself. She doesn't even let her husband go anywhere with his son because she's afraid she will need him. Also, she is no longer loving and growing more hateful as time goes. Now its to the point where she doesn't even call to check on anyone. She doesn't clean the house anymore or make dinner and my stepdad does it all. She literrlly sits on the couch at least 12 hours a day and is in bed the rest. My step sister had open heart surgery last Tuesday and she didn't even go because she said she was too sick. It's gotten to the point that I think she has just given up.

Hospital Visit...
About 1 month ago she went to the hospital and got admitted because she said she couldn't eat anything without getting sick. The doctors all said she was fine and nothing should be preventing her to eat, but she refused to leave until they fixed her. The hospital ended up bringing in 4 psychiatrists or therapists (not sure which) to talk to her, but she refused them all. She finally left even though she didn't want to. I visited her the other day and she is very pale and looks like she is on her death bed. I'm not sure if it really is gastroparesis or if it's just because she's not eating enough.

What could be the issue...
Is her mind making up these symptoms up somehow? Are some of the symptoms related to a so called couch potato syndrome? Has my siblings basically broke her from all the stresses on her throughout her life? Did the mini stroke do something? I have no idea what to do. Not sure if her symptoms are explained by a mental illness of some kind. Any advice would be greatly appreciated.