First, our eyes need to produce a certain amount of tears to ensure that they stay moist and comfortable. And another common reason is when you eyes get inflammation, it is easy to water when you eyes get stimulation. In your case, when your eyes are under the sun, they get stimulation,you may have some inflammation so that your eyes water, or just because of the first normal reason.
You'd better go to see the doctor and have a full check on the eyes. I'm afraid that your eyes get the problem of inflammation. You'd better have a good rest for the eyes now. You should not use the computer too much time now. Go to the hospital as soon as possible.
It seems you are sensitive to sunlight. Are you sensitive, tearing or pain of your eyes when you in a room with bright light? If so, you'd better have it checked out by an eye doctor. That is to make sure that your eyes are okay. If you it comes out everything is Ok, you may just have a extra sensitive eyes to bright lights. If so, you can just prepare sunglasses that can help you reduce the strong lights, thus to give your comfortable vision. Good luck.