if your sinuses are blocked it has a lot to do with neck posture. When I was laying in bed I tucked my neck back and it also straightens my back. keep in mind you can’t use a pillow on ur neck it completely messes it up. Instead put it underneath ur knees so ur knees are a bit bent and pelvic floor feels Good( you can skip that pillow part if ur pelvic floor feels uncomfortable) . When I tucked my neck back I felt the Eustachian tubes open up cuz my jaw wasn’t interfering with it anymore. once they opened up air flow was much easier to Pass through. Try and be as relaxed as u can Ofc and if u have pelvic issues, bending ur knees ( like a 90 percent angle type) and keeping ur feet flat on the bed.