Swollen knee?

My daughter has Digeorge Syndrome. She just turned 1. She sees a physical therapist once a week because of developemental delays. The therapist noticed her left knee looking kind of puffy. I took her to the doctor yesterday and they took some x-rays. I am still waiting for the results:( When we were there they had no idea as to why and said they didnt think it was related to her syndrome but that maybe she left it bent to long and thats why its swollen and it wont straighten out. I dont really believe that thats the reason because my daughter rolls around all day and when I think about it she would only stand in her walker with one leg and the other bent. Do you guys have any idea as to why or if maybe it could be related to her syndrome. I know there are so many things associated with it and maybe this could possibly be a symtom of weak joints or something. Help! Thanks:)