I've been having this problem for a while. A lot of time after races I would get a really bad headache and wouldn't be able to focus or do or want to do anything for a while other than sleep. Know that I've kicked up my training I'm starting to have the problem after hard training rides. My first thought would be that it is dehydration but I hydrate pretty well during training and after. I also have a recovery drink after every ride. I can't figure it out but it's kind of killing my day since after I train I don't want to do anything. Any ideas would be appreciated. Thanks.