Toddler Dog allergy?

I am getting concerned about my 2 yr old he has been having stuffy nose since last year! Never went away is this normal?

We do have pets a German Shepard and a New addition Short hair Cat.

Well our dog sheds a LOT talking about I have to vacuum every hour or two! 😣 and its getting very inconvenient now that im 7 months pregnant!

I’m really concerned if my son is allergic to dogs hair? Is this common? Or too early to be allergic? I dont think its the cat because we just got him and my son’s problem has been going on since he was a year old.

Also when we go to my inlaws they also have a dog and he sneezes there too, my inlaw keep her house really clean and dust free besides dog hair!

But when we go to my friends without pets he is fine all day :( sorry bout long post.

Is there some kind of test to determine allergic reaction to pets hair? Or any test we could have done? thank you!