Hi, My Boyfriend Has Really Bad Chills And A Head

Hi, my boyfriend has really bad chills and a head ache. He was fine yesterday, but this morning he felt like he was catching a cold. I didn't talk to him the rest of the day until 1 am this morning 1/5/17. When i called him he was shivering really bad i could even hear it in his voice.
What can he do to help with the chills?
Is it possible he could have the flu?
What are so e other possible illnesses he could have?
Should he see a doctor or go to patient first?

Thank you,
Leila