My husband had two fillings put in 2 days ago. one of the teeth was badly infected, close to needing a root canal. today he has a high fever. related?

Possibly: His dentist should reevaluate that tooth to see if rooroot canal therapy is indicated

Could be: Or could be coincidental. High fever may indicate abscesses tooth, a serious infection. Contact his Dentist immediately.

Yes, tooth abscess: With a tooth infection/abscess, you can suffer nausea, fever, chills and generally ill feeling. A dental abscess will not get better on its own, therefore, visit to your dentist is important.