Cockatiel Health Questions

Question
I have a male, approximately 12 years old cockatiel. He only likes to eat millett & small parakeet type seeds and bread, although I've tried. He used to whistle and has  been pretty healthy, until now I have a concern. I've noticed the last few weeks his poop seems to smell and seems more green and loose. I'm not sure if it's just the seeds because sometimes I change brands. Also I recently noticed  he has  dark brown coloring above his nostrils, it could have been there earlier, but I just noticed it now. I was worried it was blood, but not sure it looks more brown, than red to me. Wasn't sure if it's the feathers changed colors or it's a discharge? Otherwise he seems himself and otherwise doesn't look sick. He had stopped whistling about a year now, but I was wondering if it has anything to do with his age? Anyhow my main concern is his health now, please advise me. Thank You!

Answer
Hello Sharon and thank you for your post.
The fact that his stools have changed color and texture concerns me.  It sounds like you have a bird that is sick, and is so far doing a good job of hiding this (which is what a bird does very well until it's too late to keep from becoming prey).
This could be a vitamin deficiency from his diet.  
The dark brown above his nostrils may be blood feathers that are growing out, which is normal, but it could be something more serious.
At 12 years old, he should still be whistling.
I recommend that you take him into a Certified Avian/Exotic Animal Vet to have him check out.  He may have an ongoing infection that has just recently decided to surface, or he may have a parasite, such as worms (which is not uncommon, but still needs to be treated ASAP).

Please keep me updated on how he's doing.

Good luck and God Bless.
Dianna