Passing out/rapid heart rate rate

Age56

Sex F

Height 5’2”

Weight 125

Race:

Duration of complaint : new

Location U.S.

Any existing relevant medical issues orthostatic hypotension

Current medications hormones

I’ve had orthostatic hypotension for a few years. No known case. Had eval that was otherwise normal. Cardiologist examined me 6 months prior because of a surgery and deemed my heart to be healthy. Over the past two days, I started having rapid heart rate and shortness of breath in addition the passing out upon standing . Only relevant thing I can think to add is that until last Monday I was sick with some bug that wasn’t Covid (or that tested negative for Covid using a home test) I was in bed a lot for two weeks, but started moving around on Monday.

1. what tests should I have?
2. what could cause this?