Your dentist was right. Nerve injury caused by mandibular block anesthesia generally involes unilateral lower jaw, gum, tongue as well as lower lip. The involvement never crosses midline. Seeing a neurologist is advised.
The injection for your lower molars does not affect the upper lips, or nose...couldn't even if you tried. Nerve damage also comes in the form of numbness or tingling, not any of the symptoms you describe. I would agree with scott, you should see a neurologist.
Thanks for all of the advice. I do think it's an odd coincidence that I never had these pains until the exact day I had dental work done. I have had tons of dental work done in the past and never had a problem, Now I'm afraid to have anything done. I still feel like it must be related somehow.