This type of pain comes from irritation, infection or damage to the outer structures of the eye.
It can be presenting symptom of conjuctivitis, or very often a result from a corneal abrasions.
Cornea is the clear part of the eye, and abrasion is a painful scrape or scratch of its surface.
There are different causes for corneal abrasions, like small particles carried with the wind hitting your eye, or a foreign body, such as a piece of sand or wood, lodging under the upper lid and causing scratches of the corneal surface every time that you blink.
Wearing contact lens has a risk for corneal injury, too.
Try to rest your eyes as much as you can, and use artificial tears.
You should feel better after 2 days if this is a simple damage to the cornea.
If the condition is getting worse and you develop new symptoms, contact your ophthalmologist!

Best wishes!