Nourishment questions for exercising.

Usually when im done exercising and head to work I get a headache. Anybody have any suggestions for me on what I could take to help this? I actually had a big meal around 3 hours ago. Scallops at hibachi so im not really hungry just a headache.

I take some multivitamins every day and in the past ive noticed that my pee will be dark after (been told this is due to my body getting rid of vitamins it doesnt need) but my pee comes out clear.

I only do cardio when exercising, no weights or anything. Any ideas or suggestions would be appreciated.