Mother in Law (85) with chronic pain that is verbally abusive. Dr says it is not dementia. What can we do?

Hello
I posted her a few months back about difficult mother in law that was verbally abusive and she was accusing me of stealing from her then finding the items she said I stole from her. Her son, my spouse has asked her not to keep accusing me of taking her things and she says her things are disappearing and I took them. He has talked to her Dr with my MIL in the room and mentioned her behavior towards me, of course she was very angry and yelled at him. Dr is saying she is acting this way because of chronic headaches and neck pain that she has had for years and this is not dementia and doesn't think she needs to have a psych evaluation for it. The Dr is trying again to refer her to a pain specialist to treat her even though it was the same specialist that was not able to help her successfully in the past. The referrals for the specialists could take months if they are covered at all and these Drs may not be able to do anything. She is already on Trazadone and Xanax, but nothing is helping her anger outbursts. What can we do at this point? This woman is 85 years old, Dr says she only has chronic pain but she is real pain to live with, so far she has been yelling and screaming at my husband and me and has not hit either of us but my husband told me she was close to slapping his face. She is making me stressed out. Any advice?