Why Do I Feel Lightheaded When Changing Positions In Bed?

The past week I have been lightheaded, mostly when changing positions in bed & going from standing to prone position, going from side to side. Some days I've felt better than others. Tonight I have also felt lightheaded when upright & my heart feels like it's pumping steady but hard. Using a wrist BP device (not sure how accurate it may be), I got 127/44, pulse 90. A couple times last week when I didn't feel quite as well, the lower number on the BP was also lower than usual (in the 50's) like tonight.

I am 53, have CHF - take Lisinipril & Coreg & Furosemide & KDur as well as a couple inhalers for my bronchial asthma. Have had a pacemaker/defib since 2004. For the last 15 years have weighed around 370.

When I started feeling like this earlier tonight, I took two baby aspirin. It helped minimally.

I am a musician & need to play for a funeral in the morning. If I feel like this tomorrow after the funeral, I will probably go see my cardiologist or MD. Tonight I just want to get through, get some rest, & be able to play in the morning. Surely don't want to go to ER.

I am trying to drink more water in case I may be dehydrated. Also have gotten a ZPAC antibiotic from my allergist (which I was going to start tomorrow) in case this is a sinus infection causing the vertigo.

Any insights would be helpful. Thanks. Joanne