K.B.
I'm sorry, but its simply not acceptable for your doctor to say he doesn't know what it is and then tell you an allergist won't help much. If he doesn't know what it is, how can he possibly know that an allergist won't help? Ok, maybe they won't, but you have to start somewhere. If you narrow it down from the allergist that its not an allergic reaction you can move to a dermatologist, a dentist etc. Since the Zyrtec helps, then you can safely assume that it is possibly an allergy and start there.
If you are on an HMO and need a referral to see a specialist, call the doctor and insist on a referral. If not, then seek one out yourself. I've worked in the medical field and believe me, doctors don't know everything and with many of them you have to insist on good care. Its not that they are bad doctors, its just that its not as much a priority to them as it is to you. You can bet that if the doctor was experiencing what you are, he wouldn't take "I don't know" for an answer. You don't have to be rude about it, but you do sometimes have to be assertive. Just say, "you know, maybe you're right, maybe the allergist won't help but this is making me miserable enough to try anything. So please, refer me to someone." I tell everyone, in medical matters, we have to be our own best advocate (and our children's.) Don't sell yourself short.