Hi, I have 4 week old cockatiel chicks. This is my first time and the parents first time too. One chick is teenie tiny compared to the other three. I thought maybe he wasn't getting fed but his crop was full when I looked. I picked him up to take a look because he also keeps wandering far away from the rest of the babies. I noticed he has a huge red lump or growth on his belly. Is there anything I should try to do for the baby or do I just let nature take it's course. I also noticed the parents seem to take a long time away from the chicks, is that normal? Thank you so much for any advice you can give.