Abnormal beak growth?

Question
I have a budgie who we found in our backyard who's beak is growing
abnormally fast. (I do not know it's age; we believe he is male.) We have
gotten it clipped twice already, but it just keeps growing back. We've taken
him to the vet for the clipping - aside from that, they said, he is perfectly
healthy and the growth does not seem to impair his abilities to eat or groom
himself. It is however now wickedly long and our vet has retired; she was the
only avian vet at our local pet hospital. We are very worried that this beak will
grow and curl into his throat or impair his eating. This evening as I walked
into the room where the cage is, I noticed him shivering when the other three
birds (cockatiel, lovebird, and another budgie) appeared to be fine. We live in
a sunny climate and the room did not feel cold to me; perhaps I am
overreacting.
I searched abnormal beak growth on the 'net, and all I found was a virus
called PBFD, I think - but all the pictures there were of affected feathers. This
has been going for some weeks now and his beak is the only thing affected -
could the shivering be because he is molting his feathers and we cannot see
the effect? What is causing the beak growth? Please help me, I am worried
this will become something serious.

Answer
Hi Remy,
The best advice I can give you is find another avian vet.  This could be something serious, or it could be nothing, but better safe than sorry.

If you're not entirely sure of gender, check the cere; the featherless area around the nostrils.  If its brown, its female.  If its blue or pink, its male.

If you want to keep his beak in check, apart from clipping it, try giving him wooden toys to chew on.  That can help to sort of file it down.  And they enjoy doing it!  Beak growth could be caused by anything from hormones to cancer.  Again, I recommend you ask a vet.

The shivering could be due to molting, but again, I would ask a vet.  In fact, I believe there's an "Ask the Vet" category on AllExperts.  I would still take it to a vet, but you can at least get some professional advice.

I hope this helps, and I hope your bird gets better!
-Leah