You should take notice of this. From the preliminary judge, you may get the chronic Keratitis infection. You'd better go to see the doctor as soon as possible. During this time, you should keep good habit of hygiene. In addition, don't eat the spicy food. You can eat those foods with Vitamine C to make the eyes moisture and improve the immune system.
Your eyes tearing just when you peeing? I would like to ask, if you feel pain when you peeing, if it is the pain makes you want to tear? If the answer is yes, I just suggest you go to a doctor to check your body, is there some thing wrong with your health other than only your eyes. There still has another reason I guess is about the environment where you peeing, is that water closet stink? Or heavily polluted by dirty water of has some radiation or even strongly rays? The outside factors maybe the reason which causes your tearing.