There are lots of reasons why chiropractic care could be helping his temper, reflux, for one could be causing him pain and is sometimes helped by chiropractic care. I have heard it helps with allergies, too.
Are you looking at his diet at all at this point? Is your other child sensitive to any foods, fabrics, etc?
2.5 is a tough age for all kids, tantrums are probably not going to be zero anytime soon. Are the ones he's having getting less intense as well as fewer?
Bear has no history of reflux, but his brother did as an infant.
I personally know that chiropractic helps with allergies (much to my surprise at the time I learned it).
He eats like a 2 year old... almost nothing unless he's eating EVERYTHING. We do eat a high veggie and fruit diet, mostly whole grains and not too much meat. Grandmother on my side has celiac sprue (wheat intolerance), but he shows no symptoms. Bear's brother had a milk and soy allergy as a baby, but grew out of them. Now he has an allergy to pineapple that surfaced when he was around 3. Bear hasn't shown any food allergies yet. He does have some sensitivity issues with clothes, nothing major, but it is there.
Since we started chiro with him the tantrums dropped off dramatically immediately and the duration and intensity is much more manageable as well, again just as immediately.
I totally forgot about transitions! Yah.... Let's just say they aren't one of his better times. Both of the boys have trouble with transitions, the older one is in the normal range, but Bear... well he is just intense about everything.