My son also had colic, and at first we tried to treat it based on thinking it was tummy trouble (gas), since it seemed like he was in pain (why else would a baby scream like that, right?), but it didn't make any sense. He was fine all day long and it would only happen at night, but he was nursing the same. Its not like anything changed at night as far as how he was eating. Why would he have gas only at night?
We did take him to the Dr. but they just said it was colic and it would pass eventually. Our son did not have reflux or allergies or anything like that.
Reading "The Happiest Baby on the Block" seriously saved our lives. Tight swaddle, vigorous bouncing/swinging on his side, and loud white noise like a vaccum cleaner or the exhaust fan over the stove. We bought some white noise CD's but none of them worked as well as the actual vaccum. We did end up burning out our little handi-vac.
We had thought he didn't like the swing or the bouncy vibrating seat, but then we realized that he did like them as long as they were on the highest setting. Here we were using the lowest setting, thinking it should be as gentle as possible. Same with the noise... you would think soft lullabies would be calming, but instead he likes the loud, obnoxious vaccum cleaner!
Good Luck and remember this too shall pass!