I don't know that my experience will be that helpful since I didn't know I had an intolerance to dairy for most of my life and I imagine that the noticeable symptoms differ in different age groups. But the symptoms that I now recognize to be from dairy intolerance were; sinus problems (usually congestion), fatigue (not debilitating, but I had a noticeable energy boost when I gave up dairy), and diarrhea. For me, the GI problems would typically take 12 or more hours to develop (which is why I didn't realize for so long that they were linked to dairy).
I'm not sure this statement is true:
"While allergies do run on a spectrum, if the person doesn't need to carry epi pens because they could die from exposure, allergy isn't the correct term. IgE allergies are diagnosis with testing that isn't all that accurate and clinical presentation. If the Dr. isn't sending you out the door with a script for epi's then it's an intolerance. Same treatment in avoiding but obviously very different results from exposure."
You can be allergic and not be in danger of anaphylaxis. If exposure to something gives you a histamine reaction that includes hives larger than 3mm, that is considered an allergy according to the allergist I met with a couple of months ago. So while I am allergic to grass because it can cause me to break out into hives, it is not considered a life-threatening allergy and I have no need to carry an epi-pen. I have a dairy intolerance. I have a grass allergy. Clear as mud? lol