My teeth become sensitive when my allergies act up. Any tips?

It may sounds strange, but with allergies or any sinus problems my teeth become TERRIBLY sensitive. I don't even know if it makes sense. I've been told it's because of the pressure it puts on the nerves or something. I don't understand that, I won't pretend I do, but apparently it happens. I have attempted all allergy season to keep this terrible symptom from rearing it's ugly head.(Though I have much more severe symptoms, so it's not just this.) Masks, antihistamines, decongestants, the whole nine yards. But today, it has happened. And it is killing me. Sort of literally in a way. The pain is excruciating if anything touches my teeth, particularly liquid, and that's really almost all that goes in my mouth. And it's pertinent to my survival. It hurts terribly. I've tried to do it little by little anyway, but it's just so painful. I'm getting dehydrated because of this, and with all my other problems, oh I do not need that. So anyone know what I can do. Does sensodyne toothpaste and that sort of stuff work if the sensitivity is due to sinus pressure or only when it's caused by wearing down of enamel? Is there anything I can do to make this less painful. Because I REALLY need to get some fluids in me before I go to bed.