digestive problems

Hi guys, I have female cockatiel who has weak digestion. We always see undigested few seed in her poop. Not all she eats, but always some left undigested. At first we took her to the vet, we started treatment for megabacteriosis, we have seen some improvement but it didn't entirely gone. Also...

I think 4 year old Buster has a swollen crop. But before anyone jumps the gun, I'm taking her to the vet tomorrow afternoon. The crop isn't hard it's somewhat sponge-y, and she doesn't seem to be in any pain when I gently touch it. The question is, could a swollen crop be due to a change in...