Can a broken molar tooth cause swollen lymph nodes and nausea?

If infected, YES: If the tooth is infected (nerve, gum tissue or both, ) the infection may spread and create lymph node issue and other symptoms.

Swollen nodes: If merely broken? No. However that tooth, other teeth that have infections, gum infections or any infection in your head can cause swollen lymph nodes. Many individuals have chronically swollen nodes from allergies, sinusitis, etc. All tender or swollen nodes (or any lumps) should be evaluated by your physician (and dentist) as appropriate to the location and symptoms present.