What causes and swooshing heartbeat sound in ears?

I only get this when I lay down or stand up and it only lasts a few seconds. I've had my b/p checked more then 5 times in the last 8 weeks by my doctor and it's fine. Had an ECHO, holter monitor, chest xray, EKG and blood work...all normal. I do have a feeling of clogged/full ears, headcases daily for 7 weeks, eye pressure and I have anxiety. Was put on antibiotics for a possible sinus infection in May for 10 days but I don't think that has anything to do with it...any ideas?? I'm 27, female, just lost 35 pounds and the only meds I take is Xanax (.25mg when needed) and a daily vitamin.