Hi E., both of my kids had/have reflux. My 4 year old outgrew it by the time he was 1, and my 11 month old is still showing signs.
They were both put on medication at 2 weeks old, zantac for the first, and zantac + prevacid for my daughter.
It is painful for them, and damaging to their esophagus. My son spit up A LOT, but my daughter doesn't. She has what's called silent relux, where it comes up but not out, and has to go back down which is twice as painful. The medications work differently, some neutralize the acids and others help lessen production of the acids.
I second the rolling up the towel under the mattress until you can get a wedge...other ideas are feeding smaller amounts more frequently, keep her upright for at least 30 minutes after each feeding, we also put rice cereal in their bottles (some peds are ok with this, others say it doesn't help at all....but I could see a major difference with both kids)
I'm not sure if you're breastfeeding or formula feeding, but I would also suggest asking the dr about milk and/or soy allergy. The symptoms are very similar to reflux and a lot of the times go hand in hand...screaming, obvious stomach pain, spitting up (sometimes) Both of my kids were also allergic to milk and soy. We had to give them both a special formula (alimentum).
It's a long road for some in getting the right diagnosis and treatment. Don't give up and if you know something just isn't right with her, don't take no for an answer. We had a tough time with our ped actually admitting our first had reflux (she just kept saying he was colicky) If you have any other questions please feel free to contact me. I hope she's feeling better soon, poor thing.