Our little guy had an "itchy trigger" at around the same age. At his one year appointment, the pediatrician told us that this is not atypical for toddlers to do with foods that they don't like. We knew it was an issue with his gag reflex and not an allergy because it happened when he was eating (swallowing) and not afterwards. All we did was to make sure that his food was cut into extremely small bites, continued to offer him variety without forcing him to eat something he didn't like, and made sure that he didn't put too much into his mouth at one time. The other thing that seemed to help was talking him through it - if he started to get upset or to gag, we said "it's OK, take your time, look at me, etc.". We even allowed him to retrieve something from his mouth with his fingers when too much food was the cause of the gag, but I know that's a risky business...
One more thing I'll mention... At one point, he ended up with an acid reflux problem that was due (in my opinion) to a few too many up-chucks. A couple of weeks on Prevacid and he recovered, took him off the meds and all was well. I mention this only because sometimes the problem seemed to magnify itself, and then we had to be even more vigilant until the throat irritation had time to heal.
Hang in there. I know it's not pretty right now, but there are worse messes to clean ;)