Please Help - Ringneck Dove with Wing Problem

I have a pet ringneck dove (10 years old) who has always been in good
health. About a month ago he started picking at right wing. This
continued for days and he was obsessed with it. Although he ate well
his behavior completely changed and he became very nervous. I called
up a dove and pigeon breeder in the city and he stopped by the house
to have a look at the wing. The problem was a primary flight feather
that was not growing in normal. The breeder pulled the feather and my
bird was back to normal by the next day. There was no bleeding when
the feather came out.

Two weeks have passed since the feather was pulled and now the dove is
back picking at the same feather as it is growing in. This time he is
a lot more quiet than normal, it looks like he might be starting to
molt but he is constantly pulling at the new feather more than he is
preening. Again he eats well but has lost interest in every day
activities. I called up the breeeder and he gave me an anti-picking
spray to try on the problem area of the wing but it seems to provide
no relief.

I don't know if the feather is causing the poor little guy pain or
what but he has not been himself today. The breeder says he can't pull
the feather again and it will take 6 weeks to fully come in.

I've had the dove to a local vet a few years ago and he did not know
much about the species and did not help out at all. I have not come
across this situation before and I am really stressed out (and so is
the bird) and it looks like he is suffering. If you could provide any
advice on how to remedy this situation it would be greatly
appreciated. Thanks in advance.

Don