My boyfriend has been complaining of a fever, shivers and that his skin is crawling. Does anyone know what the cause could be and how we could treat it?

Sounds as though he may have the flu. While the flu is a virus and must run it's course, it is important that he be seen by a physician as it also could be bacterial in nature. Viruses run their course in a few days, but bacterial infections need antibiotics to go away.

This season is seeing high numbers in bacterial infections, so please have him phone his doctor for an appointment as soon as possible.

Thank you J_9. As a matter of fact, he just got over a very bad flu and has been healthy for the last 2 weeks. He had the flu for two weeks prior.

I wonder why his immune system has not beat it and he's got it again?

Most likely his immune system is still compromised and he was re-exposed to the virus.