Mother is not acting like herself but wont admit somethings wrong. What do I do?

Professional eval. Sounds like she would benefit by being evaluated by a qualified professional, such as a psychiatrist, psychologist, or family doctor or internist. Hopefully you can accompany her to help assure that your concerns are addressed during the visit. It may help if you can explain better why you think she is having problems. Hopefully you can persuade her to be evaluated.