Hello~I can relate to your fears, I am always worrying about things like that as well. I am thinking that your issue regarding the headache and pain behind your eyes is eye strain or dry eye. I highly suggest you see either an optometrist or an ophthalmologist, either one will give you an eye exam and then prescribe glasses if need be.
Another issue that your symptoms are pointing to are pinched nerves in your neck. Possibly seeing a chiropractor would benefit you. He/she will take some x-rays,study them and then go over the results with you. After a few treatments your pain and numbness in your arm should be a lot better.
Also, try sleeping on a cervical pillow, these pillows help support your neck while sleeping. I know if I sleep on a wrong pillow, I have headaches and arm pain.
I hope you can get your issue resolved soon, it is no fun worrying.