Ibuprofen or Naproxen sodium help a lot with headaches. Also make sure you drink a big ol' glass of water with whatever pain reliever you choose, dehydration can come about from DXM use and can cause headaches. You don't have access to any OTC pain relievers?
It's good that you're not interested in using alcohol to fix your headache, alcohol at this point would probably make you physically ill and would make your headache worse.