I've been running for 4 years now, and have done a few half marathons with no problems. But in the last few months any run over an hour has made me feel really ill. The symptoms start around an hour after I'm back from my run, and I feel sick, I've vomited a few times, awful headache, stomach ache and feeling really weak. The only thing that seems to cure it is vomiting/sleeping.
I'm hydrated, I eat the same things I've been eating before and after for the last few years (including something salty as I know that can sometimes cause problems) and nothing else has changed.
I'm currently curled up on the sofa feeling sorry for myself.
Any tips? Sympathy for my self-inflicted illness? 