I'm on antibiotics for tooth infection. I now have large swollen lymph node right in front of my ear. Is this from my tooth infection?

Possibly. The lymph gland should probably not be getting larger if the antibiotic is working, call your dentist!
Sure can be. But it should reduce in size as you tae the ab's, and disappear in 2-3 weeks, or you need a recheck. Can still be infection not sensitive to ab used, but time for an ENT exam and opinion.