I am sorry that you have had such severe pain and that you still have not obtained a diagnosis! It sounds like you have had a pretty good workup already and that several conditions have been ruled out. The symptoms that you are experiencing I think could be caused by either a neurological (nerve) problem or a musculoskeletal (rheumatological) problem. I would suggest a repeat visit with your primary care doctor
to summarize your symptoms and workup to date and to determine what other specialty workup you should receive.
The fact that the pain symptoms seem to come and go along with visual symptoms suggests to me that something called iritis or uveitis should be ruled out. These are an inflammation of the front portion of the eye, and they are often associated with various rheumatologic diseases (inflammation of the joints and connective tissues). This would be especially the case if you have any objective evidence of joint involvement, such as swelling or pain of the joints of the feet rather than just general pain in the calves.
A neuropathy (disease of the nerves) would be the other possibility, and might require advanced nerve testing as well as looking for causes (diabetes, medications, toxins, vitamin deficiencies).
Your primary care doctor will be able to make the right referrals.