My daughter is 23 months old and has many of the same issues your son has (GERD, food allergies, eczema). I remember well her phase with self-induced vomiting, she stuck her hand/spoons/whatever down her throat and just gagged herself.

I think in part it was related to teething, she was having some jaw pain and she wanted to gnaw on something on those back gums and she just had a super sensitive gag reflex from the GERD.

I think part of it was also her not knowing what to do with the sensation of feeling "full". At a year we were introducing new foods and she was eating more solids and so was getting new feelings of fullness and because of the severity of her GERD I think she associated fullness with the heartburn that would soon follow...and so she made herself throwup for some relief.

And I think partly it was for attention. It got a reaction from us, of course, and so we were sort of unwittingly reinforcing the behavior. Also, when she threw up we always stopped feeding her and so she was sort of using vomiting to tell us she was done with her meal.

So here's what we did: I gave her Tylenol about 30 minutes before meals and gave her a frozen washcloth balled up that she could gnaw on. That helped calm the jaw pain from the teething and made wanting to gnaw on things for comfort not an issue during the meal.

We went to feeding her very tiny meals like 8 times a day...like 2oz here and 4oz there. We paid attention to any cues that she might be feeling full, if she gagged at all or if she turned her head even once, we didn't try to get her attention again, rather we just ended the meal.

We taught her the sign for "done", which is just moving your arms in front of you (like an ump does when he says "safe") and we would say "done!". We stopped acting alarmed when she did vomit...we put one of my husband's old Tshirts over her as a body-bib and we put a mat on the floor and when she puked we would just say, "You don't have to throw up, if you're finished eating then say "Done!" (and we made the sign too)" and then we would whip off the tshirt and pick up the mat. Clean up was quick and there wasn't much of tadoo around it and we were giving her another tool to communicate with us that she was finished.

After about 3 weeks it worked for us. Of course I should say that we went for months with the puking and finally had a speech therapist/feeding specialist come in and work with us in order to come up with the game plan that we had. When she first started doing it I was as frustrated as can be!

Good luck, hope this helps!

Another thought (like my first thought wasn't long enough, lol) is that maybe he's having an allergic reaction? Vomiting can be a sign of allergy in little ones, which I'm sure you know. Maybe he's sticking his fist down there because it's feeling itchy or swollen? Maybe he's developed a new allergy to a food he's always tolerated before? Just a thought!

Thank you so much for taking the time to send this information. I'll definitely try some of these ideas. We've already been working on the signs for drink, eat and please. :)