C.,
Welcome to parenthood. Welcome to infant colic. Come to think of it, welcome to reflux as well. Very common. Very difficult when you have such a new little one. We can all attest to that.
Things to try are (1) rocking your little girl in a "football" hold, and gently jostling her while doing so. Very rhythmic and soothing for them. Also try a "shushing" sound, almost like what the surf sounds like when it comes up on shore, very close to her ear. This is a type of "white noise" and helps a lot with a little one's crankiest momemts.
If it does turn out to be reflux, and only your ped can tell for sure, there are a few medications that help them a lot -- Xantac being one. It's in liquid form, and dispensed just like Tylenol would be -- with a dropper.
Also, don't be afraid to pass her off, if you can, to your partner. She won't die of crying, and it might conserve a bit of your sanity. This tends to relieve itseld after about six months or so, so content yourself with the fact that it's not permanent.
Good luck.
E.