Sometimes--not always--but sometimes, digestive and other issues can be treated with pediatric craniosacral therapy. This is performed by a pediatric chiropractor/craniosacral therapist. While some feel that this emergent practice is a bit "woo woo", we have taken our son to receive craniosacral therapy since he was two weeks old and we have had nothing but positive experiences. He is now 3 and goes every other month or so for adjustments. We believe this keeps his body's systems in balance, boosts immune support (he hardly ever gets really sick) and just generally helps to support his body's growing well.
One thing I have learned from reading chiropractic papers (for my own education) is that studies have been published in Europe which show an encouragingly high rate of success in treating colic in babies. Over 75% of the children in the study were relieved of colic symptoms over a short series of treatments. Colic is one of those mystery afflictions; some professionals treat it as GERD (or your reflux) and there's also been some research which points to an underdeveloped nervous system--(babies are either overstimulated and cry in response or understimulated and cry in order to create the stimulation they are needing.)
Of course, you should talk to a professional about this, because it may not be the case at all with your child. I'd suggest logging on to your favorite SeattleMama sort of site and asking other moms for referrals in your area. Or you might consider calling Dr. Elise Hewitt at Portland Chiropractic Group here in Portland to see if she has any referrals. I suggest this as A. she's our son's doc and B. She's a founding member of the association of pediatric chiropractors and pioneered the work here in Oregon.
I've already written a lot, so if you want more information, feel free to message me. Once again, I'm not saying this will be 100% effective for your son, but I've seen and heard, time and again, that this is a worthy option to consider. I've also worked with children for nearly 20 years and have seen a lot of medical issues with children, and I am very, very cautious about medical care for my own son, so I am not suggesting anything that I haven't done myself. Best wishes!