I had two crowns on my back molars almost a year ago. Could the doctor possibly have hit the end edge of facial nerve?

When working in the back of the mouth, dentists usually numb you up by doing a lower jaw block. In doing so,  your lower jaw nerve (mandibular branch of your Cranial Nerve 5, not Facial nerve which is Cranial Nerve 7) may be disturbed or injured. If that nerve was injured during your crown procedure, then it would not had shown any of your pain symptoms. Temporary or permanent numbness of the lips and teeth are the most common signs of lower jaw numb injury. Your symptoms are not likely due to your prior dental work done.