Do i have gallstones or indegestion ?

I have suffered over the past month with sporadic severe upper abdominal pain which is really painful,comes on quickly usually waking me in the early morning,the pain is severe & and makes me vomit.It lasts for about half an hour and i get hot and clammy and no position makes it feel any better-then as soon as it started after 40 mins or so it gets better and then im fine with no symptoms at all.I thought it may be gallstones - 6 weeks ago i started a low fat diet and have lost 10 pounds and it is since that time the pains have begun,im female & 40 so went to doctors expecting him to suspect gallstones -despite me explaining the symptoms he gave me medication for acid reflux which i am certain i do not have ?? How can i get tested for gallstones if my doctor didnt even suspect i have this ?im reluctant to use the mepradec he prescribed since its for acid indegestion and i dont suffer with heartburn ?should i do as doc says and take the medication even though i have no faith in his diagnosis?