Help with mom?

So I’m not looking for anyone to diagnose her and I’m not about self diagnosing. However I would atleast like someone to help me atleast be in the ball park with what to research and what to present to a doctor to see their professional opinion.

My mother is struggling recently with what appears to be depression due to her situation(I’m not a doctor so I can’t diagnose this but it appears to be so and I’m sure if she was a evaluated they would probably say that she is currently dealing with depression).

My whole life and it has worsened over the years my mother has a very distorted perception of things people say about her and things that happen. With certain things in my childhood she has misconstrued for just one example what age I was when I was in the hospital for a panic attack (there are medical records so I know I was right about the age but she argued it anyways). She says my grandmother treats her like a failure and has a terrible relationship with her, even though I’ve seen them talk on the phone and in person and be completely fine even laughing together and my grandmother who I’m very close with always praises her highly by saying how great of a mom she is and always speaks highly of her. When we argue sometimes she’ll say I said something that I absolutely did not say and be offended by something I never said. When my sister acts up like she often does my mom will go on and on about how horrible she is to deal with and how mean she is and then after it passes she’ll completely deny ever making those statements or that my sisters is completely fine. There are many more examples I can give but these were just the few that came to mind.

She’s always kind of been like this exaggerating certain stories, making completely false accusations about what someone thinks about her, having a distorted perception of what people say and what people think about her. It has appeared to have gotten worse over the years since I’ve noticed my step dad actually goes on her side when she makes false claims which I think that just adds fuel to the fire. For example when we were making my baby shower invitations I said “I’ll just do it myself because you’re not going to do it how I want it done”, my mom responded “right I’m an asshole who can’t do anything” I said “I didn’t say that please don’t put words in my mouth” and my step father then said “but you mine as well have”. Just feeding into her delusional behavior.

I really care about my mom and want to get her help I just don’t really know where to begin or how to search engine that. I’m hoping someone could maybe point me in the right direction.