Have you seen an HCM specialist yet? I'd strongly recommend it - HCM management is specialized enough that most cardiologists, no matter how good, aren't completely up to date on it.
To learn more about the questions you should be asking, I'd suggest making a call to the HCMA office ((973) 983-7429). They have these conversations with newly-diagnosed people quite often, so they're really good at it. They can also make some suggestions about specialists that you might see.
In the meanwhile, it might help you at night a bit if you slept with your head elevated. The easiest way (I think) is to get a foam wedge (at a medical supply store, or some pharmacies) and put it under the head of your mattress.