I get background headaches and feel tired easily when bp is under 100/77 or hr over 90s. at times feel dizzy and faint when bp is under and hr over. hr is normally in 90s and goes to 100s from doing nothing. what can be done to reduce hr?

See cardiologist: There are much that can be done but the 1st step would be to find the cause for your symptoms. If you have already consulted an internal medicine doctor, the next step would be a cardiologist.

Hydrate and exercise: You may have orthostatic hypotension or possibly a variant of POTS ( postural orthostatic tachycardia syndrome). Both tend to respond to hydration, and POTS tends to improve with a gradual buildup of exercise. Monitor your BP and HR in different positions and see if you are noting elevated heart rate with low blood pressure. Seek evaluation by a neurologist or cardiologist if above is positive.