Talk to General Physician on High Heart Rate

I m facing high rate n shortness of breath while climbing stairs sometimes hb is 10.8 chest xray urine s electrolite caretine thyroid all test r normal yes i do tk stress alot dr has prescribed andral 1 tablet 2 tymz a day n omeprazole 1ce aday i want 2 ask ll i b alryt n wht da cause of hight rate n omeprazole shud i tk coz i dnt feel heart burn