Migraines was the first thing suspected with my son and he was put on medication, which did in fact make him feel worse - he felt extremely dopey and put on weight and the headaches continued!  Rebecca is right though, it is certainly worth checking this out too.  I hope you get to the bottom of it before too long - I remember my son’s headache period as a nightmare time!  Seeing your child suffering and not knowing what to do to help is upsetting and frustrating.  Good luck with Cody’s specialist - I am sure he/she will  help you discover the cause and get him feeling well again soon.