Imdur is a nitrate. Toprol is a beta blocker.

If you were taking toprol for a while, then stopped, this may be part of your problem. Beta blockers must be tapered off slowly if taken for long periods, and still may have problems with higher heart rates, angina, etc after stopping. How long did you take it?

Your cardio needs to look at the entire picture as you have several factors...MVP, tachy rates, possible vasospams, and some orthostatic hypotension. One medicine may aggravate another condition. It takes time and patience to find the right combination to balance cardiac issues like this.

High platelet counts are somewhat common in autoimmune disease and inflammatory conditions. Being you are seeing a rheumy, I'm guessing one of these apply. I would indeed suggest seeing a hematologist. If you have an AI disease, you may also have other clotting issues like antiphospholipid syndrome(APS). Never hurts to have a blood work up when platelets are up.