"5 week waiting time for an "urgent" referral"

I have lost a chunk of my sight (suddenly) and preliminary exam from optician indicates a condition called Optical Neuritis. "Urgent" referral made to Opthalmologist from my GP, and when I rang up after a week to ask when I would be seen, I have been told that the referral has not been considered urgent but is re-categorised as "soon", so my appointment will take place 5 weeks after referral. Meanwhile, I am in significant pain, this condition is most debilitating and I have significant vision loss. This is not altogether a surprise as 2 years ago, identical symptoms (when I was sent straight to this Ophthalmology dept) sent me off with thyroid testing (clear); possible sinus infection (don't have sinus issues) and an ultrasound scan of my eye socket - which took place several weeks later and was clear. To send someone home (a 3 hour drive) with no follow up and that level of pain was frankly astonishing. I am not holding out much hope for my appointment at the end of May. Over 20 days and counting and this condition may have caused untold damage to my nerves by then....What to do? It would appear that a decision has been made about me before even seeing me! I. e. not urgent. I'm guessing they don't believe the early indication of Optic Neuritis in terms symptoms, my history and the professional assessment of an excellent optician and if it is not that, then what? I am so disheartened in our failing NHS and the detriment to my health by this lousy decision making.