Talk to General Physician on Dizziness And Fast Heart Rate

My mother is complaning about fast heart beat and dizziness. She is a high bp patient and she is on meds. For now she has stopped taking her meds. Since 2 days she is complaining of suffocation and fast heart beat. She thinks she will faint everything blacks out. 2 days ago she had left shoulder pain as well but its all good now. She is an over thinker. She will think abt all possible diagnosis and will get herself anxiety. What could be the reason? She checked her bp is okay sugar was a bit low but then checked again and its okay too. She is not complaining abt shoulder pain anymore but fast heart beat and dizziness still there