Bladder pain in 78 year old women who has been treated 3xs in the last year for what her doctor thought was a bladder infection with keflex, s?

Get checked. Even in an older person, recurrent urinary tract infections need to be treated, and fully evaluated. I usually refer patients for an ultrasound of their kidneys and bladder, and check to see if they empty their bladder completely when they urinate. Many things can increase the risk of bladder infections, but they can put your kidneys at risk too. See your doc, and a urologist, to be thorough.
Ref to Urologist. She probably needs work up for that. Maybe an ultrasound of the bladder and kidney with measurement of residual urine after urination to rule out obstruction or retention. I would probably refer her than urologist for cystoscopytans urodynamics too. Check the sensitivity of the bacteri causing the infection to choose the appropriate antibiotic.