Anyone have an idea what my problem might be?

So I'm not sure exactly why but there are times when I'm petting or kissing my dog and suddenly my skin starts stinging. It's not unbearable but it's irritating and doesn't go away unless I wash whatever body part is afflicted and even then that sometimes doesn't work fully.

Although it never effects my hands. Just the insides of my arms and my face and only sometimes. There are days everything is perfectly fine and I can pretty much lay on top of her and smother her head with kisses and have zero problems and then there are times where I just can't. I can still pet her but no playing with her like I usually do.

It's so strange. The only thing I can think of is my dad once told me that when I was a baby my grandmother's black lab would lick my face or somehow get saliva on my face and I'd have a reaction. It didn't seem to bother me but I'd get a welt like spot or streak on my face from where his saliva touched my skin. It didn't last long either.

But I'm an adult who's been around dogs my entire life and while my current dog is a black lab/pitbull mix she's licked my face or the underside of my arms before and I've had no negative reaction.

Only other thing I can think of is she's touching something that I am mildly allergic to but I can't figure out what the h*ll could be touching her all over her face and body to cause me to react this way. She pretty much does the same thing every day so I'm very confused.