There isn't sufficient information to give a specific diagnosis. Since it causes problems with your eyesight you should meet a neurologist so that you can be examined and undergo investigations such as X-Ray C-spine, CT/MRI(if indicated), etc. so as to find the underlying cause of the problem and have it treated accordingly. You can apply a hot water bag over the area that hurts for 10-15 mins and can apply a topical pain killer over the area after that and massage gently. Since it is affecting your eyesight any brain involvement should be ruled out.