Unknown Diagnosis?

Question
Hi, I have been breeding and raising a cute "duo" during the past 4 years. I have two budgies, one named yellowberry who to my knowledge is matured and is female and the other banana, young, timid, and rather meek compared to yellowberry and perhaps much younger. Just recently however, things came to a bleak turmoil. After a tedious daily cleaning of their cages, Banana seemed to be limping while walking and on occasions, tucked his leg on his side in an unusual fashion. I deduced possibly that maybe he injured his leg while he went flew out of the cage. 3 weeks after that, his condition worsened. After close speculation, I noticed that he was often famished at times and fatigued, tired and wanting more sleep and rest. This through my senses didn't make any sense prior to the two weeks before. He seemed very energetic and active probing through the cage and flying crazily in my room. Right now however, these symptoms as I descirbed earlier;fatigue, sore tucked leg, and hunger, are weakening Banana day by day. I am very confused as to what I should do now. Strangely enough, none of these symptoms are shown in yellowberry. Your help is sincerely appreciated.   
What I have done beforehand:
-Everyday, clean water, food, and newspaper template for cages.
-Allow them to fly in a spacious area for exercise under my administration.
-Cuttlebone in cage
-Provide them nutritional supplements, washed and fresh lettuce on a day-by-day basis.

Answer
Hello Anthony.
It is impossible for me to diagnose him with being able to examine his condition. It sounds like he may have a severe internal disease or malfunction of some kind. His condition may be genetic as I see you have been giving him and yellowberry everything they would need for a long and prosperous healthy life.
The only way to be sure of what he has, is to take him to a avian veterinarian.

So sorry I couldnt be of further help.
Best Of Luck To You and Banana.