Ball hit my eyebrow on swminnig pool 7 weeks ago. Now when I blink my eye hurts. May I have retinal detchmt.? Shall I go to ER?

No. A retinal detachment would not be painful. It presents as a painless loss of peripheral vision. If your eye hurts when you blink it could be due to a problem in the cornea, or crystal, over the colored part of the eye or due to something on the inner surface of the eyelid. I would suggest making an appointment with an ophthalmologist who should be able to help you.