Feeling faint at Dr. Appts

Shelby
Does anyone else have difficulty when OB asks you to lie back (not completely flat-propped up some) to check fundal height and baby's HR via Doppler? Today was the second time it's happened (34 weeks +2) seeing stars, nausea, sweating, feeling faint.  She does not seem concerned but I'm paranoid a tad bit about follow up appts and worry it will keep happening. I even have to get up before she is done with exam otherwise I'll pass out.    Haven't felt that way when reclining at home... Anyone else??