“What is the best medicine for colic?”

I don't think there is agreement among patients and physicians as to what colic means. It is usually used in the context of biliary colic, meaning crampy postprandial pain in the right upper quadrant (secondary to gallstones). So, you may be referring to biliary colic or perhaps colic in general, which would typically mean crampy pain somewhere in the abdomen. This type of pain has many causes and I would need more detail in order to advise better. Most crampy abdominal pain tends to be in the left lower quadrant and is associated with bowel movements. This symptom is often related to irritable bowel syndrome and thus anti-spasmotic medications (e.g., hyoscyamine, dicyclomine) can be given to relieve pain. Without more specifics, I'm afraid I cannot comment further.