There is a simple skin prick test for the allergy. What you describe actually sounds like a mild onset of the allergy. Others around here have had stomach cramps from avocados. I don't know what to make of that. But itchy mouth, throat, skin and hives are indicative of allergy, as I recall. Serious reactions include respiratory problems.
Are the other two threads I've read where people are having problems.
Here's a good tip. Never by an avocado with the stem broken off. Only buy the ones that have a nub of stem still attached to the fruit. That means it was clipped from the tree and landed in a bag. The broken ones may have been knocked out of the tree or just found on the ground for whatever reason. They do not ripen evenly. The ones with no nubs get those brown veins and if they fell, you often find a bruise.