I'd be wary of chiropractic help on an infant. If you do do it, find someone who uses an indirect technique - no whacking and cracking! My husband is an osteopathic physician who does manipulation and he is very wary of doing these types of treatments on infants as a general rule. Now if the infant truly does have dysfunction, then yes they need to have that treated. Possibly dysfunction is causing the colic. BUT a general colic treatment (across the board for all colicy babies), that I would walk away from. The physician/chiropractor needs to be very skilled in diagnosing with their hands (testing functionality of the joints) not just x raying to see if there is a difference.
In general the best advise with a colicy baby is to keep them close to you. Obviously that is tough as Mom needs to get things DONE and can't sit and hold baby 24/7. I'd suggest a sling/wrap to carry baby around in. Also swaddling can be very helpful! My infant started a fussy nighttime stage after a few weeks old. She's scream and flail around and refuse to nurse, grabbing, scratching, panicking. The swaddling blanket was such a God-send! I'd advise one that uses velcro so it doesn't loosen. She had about a week where she HAD to be in it all the time (it has a hole for car/swing seatbelts). Then it was only when she was sleeping. At 4 months she outgrew it (they come in different sizes) and I made the decision to not replace it with a larger one and let her learn to sleep without it. She had a few nights of waking multiple times, but she did learn to be without it fairly quickly.
No one can understand the havoc that a colicy baby brings to a family unless they've experienced it. Hang in there, it will get better, hopefully sooner then later.
Best wishes!