After reading your question I have come to know that the main concern you have about your mother is heart pounding which has increased in frequency and her raised blood pressure. I think the best doctor to consult right now for you is a good cardiologist.
considering her condition she require some medicine that will control her blood pressure and heart pounding. and there are medicines available like B- blockers which help in both.
If she has other symptoms like chest pain
or shortness of breath
, then he may advise some other tests.
Hope this answer would have helped you in making things clearer.
Dr. Atif Nazir