Seeing a dentist to find out source of dental infection is advised.
When your DH taps on the tooth, does it hurt? Is it painful with cold, hot or sweets?
All of these things can point to a badly infected tooth. It certainly can give him a sore throat and swollen lymph glands.
Antibiotics will only work with that kind of an infection for so long. It will reoccur unless properly addressed. He really should get to a dentist and have the tooth checked with a xray to see if there is an infection at the root.
Best to you and him,