Any experience with back pain and rapid health decline?

I'm hoping to get some answers, I'm not sure how common my mother's situation was. Me and my family are still somewhat confused as to what happened to my mother, since the doctors told her she shouldn't have been having the level of pain and suffering she was having according to the issues they found. This post does talk about suicide, just to let you know upfront. So my mother was actually totally okay with no major health issues in 2019. She had a very active life and a very active boyfriend, she was 71 and lived in a decent studio apartment right on the ocean. She liked living in that area and had her own life and her own friends. My mother was very extroverted and also loved to travel, in fact we both flew to Colorado for a vacation together in August 2019. She was also okay in May 2020, though she did complain that she kept pulling her lower back but with some heat and stretching she was able to feel normal again. I had been wanting to move to another state, to the southwest for many years (we are from the east coast), and I asked her if it was okay and she said yes, that she would actually like to spend time with me out there in the winter, so she told me to go ahead and I did. I'm not sure if it was the Covid lockdown that made her health decline, we honestly have no idea. But 5 months after I moved away she was carrying grocery packages and her wrist twisted and sprained from the weight of the packages. She got scared and called me and asked me to come home to help her (November 2020). I said I would, though with the vaccine issues and quarantining and all that, she decided she was okay and I didn't need to come home and she would let me know if she needed help. Then out of nowhere in like February 2021 she woke up super dizzy and weak. She got checked out by a few different doctors and they were saying it was fluid in her ears from allergies, and some vertigo, etc. She said her legs felt like rubber, very weak, but sometimes she got her energy back. Around this time she stopped driving, and her boyfriend (who was 72) drove her around though he said he was getting worn out. I decided to move back east and be closer to her. She wanted to stay close to the ocean, like within 15 mins drive time and I really couldn't afford a place in that area. She decided she would rather stay in her apartment since she was also having good days and enjoyed walking on the boardwalk. I moved into a townhouse in an area I could afford that was a bit of a drive but it was fine and I loved seeing her again. When I went to see her that summer, she was no longer her bubbly happy self, she was not smiling at all. When I left the year before, she was happy and joking around. Even my boyfriend noticed that she was not herself anymore. Not happy, always using alcohol disinfectant wipes, telling me I could only sit on the sofa and not her chair, insisting I wash my hands as soon as I walk in. She said she was having bad back pain and she was using Solonopas for it a lot, also her doctors starting prescribing her heavy painkillers, muscle relaxants, gabapentin. She got a steroid shot for the pain, like an epidural. It didn't work and she ended up with a bad fungus infection on her feet instead, and that took time to heal. Then she got tendenitis in her wrists and thumb and had to wear wrist wraps. She was in pain much of the time now, also bad jaw pain. All of this happened within 10 months! She was not taking her pain killers other than advil and the muscle relaxants sometimes, because she was worried about being constipated. She was also diagnosed with osteoporosis years ago, and recently diagnosed with mild spinal stenosis. I saw her once a week or every other week to help her with laundry and food shopping. Then in November a detective contacted me and came to my house to tell me she committed suicide by train. We were talking the night before about her jaw pain. I'm devastated and confused.