One of my daughters felt like this, very distressing for her and whole family and was off work for a long time. I went with her to hospital therapist - no good there; medication then from doctor which she still (years on) resorts to occasionally, but I'm sure it was a combination of things i.e. medicine, true grit, having young children dependent upon her and an idea I had which she tried and found helpful. The 'idea' was something I use every day to assist me in art work - it has been known to help people (one my mother) with the condition "S.A.D." - buy yourself a daylight bulb and use it every day, preferably in front of you to present daylight to your optic nerves. Try it for a week or so, they are obtainable from electrical stores, some supermarkets and any craft shop, they're blue but don't shine blue, about �6.