Vizsla's are considered to be soft by most trainers...They also tend to break out late, as in be steady to wing and shot later than shorthairs or pointers.
It sounds to me like you may have started the breaking process to early for this dog. Perhaps you started the dog on pheseant first rather than smaller quail to get em started. What you're describing does not sound like a dog that is gun shy, but if the dog handled birds well for the first two weeks, what changed at two weeks. Did the dog take a spur in the face, did you shoot a 12 over her first, or did you hit her with an ecollar prior to the dog being collar conditioned?
Dogs react to stimulus, they just don't become shy on their own.
Without seeing the dog it is hard to tell you what you should do, but if it were me, I would get back to having the dog have fun, plant a quail or whatever you don't typically hunt, which she doesn't have any negative connection with. Praise her when she finds it, give her a treat, stroke her back (with the fur) push her butt towards the bird before you flush it (this should increase intensity). Use a higher voice then you typically do, be very gentle, do not use the gun until she's seems to have regained her intensity.
There are many ways to try and fix a dog that is scared of birds, some of these could make the dog worse, or could create other problems that you will have to solve later. First off do not use an ecollar or do anything but positive reinforcement. You will have to be patient and disiplined in order to help this animal, you can not lose your temper if things are not going well, instead if you find yourself to be frustrated put the dog up for the day and try again tomarrow.
Does she like to play fetch, kill a quail and freeze it, and do not play fetch with her unless it is with a frozen bird. Get the phesant wing out, see if she'll sight point it and chase it. Cut down on her food for a couple days, and play fetch with her with a dead quail, let her eat it, put one in her kennel so that she is constantly around bird scent. Everything you do should involve a game which invovles bird scent, and making it fun for her again.
Best of luck,