Unless they can prove a bacterial infection with a temperature, the advice you will receive is just that - rest, fluids and pain relief. Follow your instincts and take him in to the doctor if you are sure something is really wrong, but normal processes such as teething do cause temperatures and you shouldn't be too worried unless you notice a number of other symptoms that alarm you.
Just for the record, teething can also upset the digestive system and cause diarrhoea as a common side-effect.

Kerrie