My 19 year old son was 10 minutes into some basketball hoops when he experienced some shortness of breath. He cam home and laid down. About 10 minutes later, and iwthin 2 minutes or so he developed an intense headache, accompanied by fever and intense cold and shivering. So intense was the headache that I was unable to drive him to hospital and I called the paramedics. They came immediately and in a few minutes the fever was gone andthe headache subsided somewhat. I took him to hospital emergency and over the course of 10 hours there, he was given a CT and Lumbar Puncture (LP) which were both negative, ruling out things like anurysm and meningitis. That is what we were told. We were also told that the LP would result in backache and additional headache for about 5 days. The headaches persisted for 5 days as promised, which we treated with Tylenol 3. It is noe gradually subsiding, and we hope it will do so totally. Question: What caused it in hte first place?