What Causes Loose Bowels Along With Severe Headaches?

Hi I have had a headache, I went running this morning and didn t drink before and only had a little bit after. After 2hrs it dosent hurt only if you shake it. I kept on weeping about three times. About 1 to 2hrs later I needed to do poo it came out like a normal poo but than went to soft runny poos. I then needed to go again and nothing really came out was just watery farts, it was yellow. I haven t vomited or felt like vomiting. I m quite hungry