Dumb doctor!! This is almost certainly benign paroxysmal positional vertigo (BPPV). Lying down, getting out of bed, and turning from side to side in bed are the classic triggers for BPPV attacks, and the short duration (few seconds) is also classic.
Any doctor who says "nothing you can do about it" is WAAAY behind the times.
The American Academy of Neurology (I believe) just announced--finally, 16 years after Dr. Epley published his paper about it!--that the canalith repositioning maneuver, aka the Epley maneuver, is standard treatment for this. Even though studies long ago showed that this maneuver is an instant cure in 80-90 percent of cases.
Good news--BPPV is not serious (that's why it's called "benign") and is easily curable by a simple, noninvasive, quick series of head movements.
What you need to do is find another doctor who has made the effort to learn this maneuver. Most ENTs (though by no means all of them!) will know. General doctors SHOULD know how to do it, because it's so simple, and BPPV is so common, especially as people age. But most of them don't.
Call up an ENT's office and ask if they do the Epley manuever. If they say no, keep calling til you find one that does. Some ENTs won't do it out of PRIDE, presumably, because Dr. Epley's idea was initially thought to be crazy and some doctors don't like him. The Epley manuever is now the accepted standard of care for BPPV.
Alternatively, a vestibular physical therapist will surely know how to do this.
And another alternative--if you have no neck issues, no danger of stroke, etc., go to Dr. Tiim Hain's Web site and look at the description and illustration of the maneuver there. You might be able to do it yourself at home. All you need is a bed. However, if you have ANY neck problems or other health problems, don't do it yourself without seeing a doctor first. Here is Dr. Hain's site:
Here are a couple of other sites on BPPV:
Good luck--and if the BPPV recurs after the manuever (which it sometimes does) you can just do the manuever again. RARE cases might need further treatment of some sort. Just find a knowledgeable and up-to-date ENT.