I use Nexium which is similar to Prevacid. You can try the new Prilosec OTC. It contains the same active ingredient as the old Prilosec (omeperazole) how it is formulated a bit differently. It is in a tablet form and not a capsule with the little beads inside. It absolutely did not work for me and within 3 days of taking it I was nauseous. My pharmacist told me that he has had many complaints of the Prilosec OTC not working for people when regular prescription Prilosec did. The whole delivery system is just screwed up and he thinks they should have never made the OTC version the way they did.
But, it is possible it could work for you. If it did not, I would try to use a double dose of Pepcid AC, Tagamet, or Zantac. The over-the-counter dosage listed on the box is about half of what you would get if you got it via prescription.