What Causes Fever Along With Vomiting And Pain In The Hands?

My 34 year old son has these symptoms which have gotten increasingly worse over the past three weeks: fever, nausea and vomiting, pain in feet, hands and neck - not continuously in all, but rather moving from place to place. This is a totally new experience since the onset. He visited an Urgent care facility and was sent to an ER. There they took an Xray, did a cat-scan, and drew blood. He was treated for a 102 degree fever and dehydration. This was on Aug. 21. He is not able to keep much in his stomach, today vomiting chicken noodle soup as soon as he tried eating it. Today his left hand is the center of pain as well as being swollen. He spent the night at our house after traveling in from his home/workplace 3 hrs away. He hasn t had a primary physician since moving to his job site, so no follow up on the ER tests. Please give me some idea of what this could be. Thank you!