I tried a piece of candy and had colicky abdominal pain and nausea afterwards. could i be allergic or is it something else?

Possible: Possible it is an allergic reaction, however not likely if no hives or vomiting or other allergic symptoms. Maybe just an intolerance

Words matter: Candy is often a mixture of many different components, one of which you appear to have reacted to.What you call it is irrelevant. You did not mention breaking out, swelling in your throat or difficulty breathing so allergic anaphylaxis is out. You would be best served by finding out the ingredients of that product and narrowing down what set you off, so you can avoid it.