Could my mother's CHF symptoms simply be sporadic or should we call the doctor?

My mother is 96 and lives out of state with my sister who is primary care giver. Mom was diagnosed some years ago with CHF, congestive heart failure - and has had symptoms which have increasingly become more incapacitating - fatigue, shortness of breath, etc. We have had discussions about end of life and her emphatic "no hospitalization". Yesterday my sister called and my mother was experiencing intermittent chest pains (described as "bursting"), left side, radiating down her left arm (sometimes right arm as well) and ending with a tingling sensation in her fingers and hand numbness. She had five or six of these "episodes" during the day yesterday, lasting less than a minute. My sister administered her nitro pills, but this didn't seem to help. My mother also complained of pain when urinating - although there is output. Today she is feeling better - but still adamant about not going to the doctor. I guess my question is can someone have these symptoms sporadically and at what point do you consult the MD?