Health question about my baby degu?

I work at an animal sanctuary and almost 2 weeks ago one of our Degus had 6 babies. A couple days later when I went into work I discovered the mom dead and the 6 babies extremely close to death. One of the babies died before I left work. Seeing as my boss didn't think he could do anything about it..my friend took 3 of the babies, and I took two. Hers died on the second day because they were in terrible shape. But mine have survived. However, one of my babies died yesterday. He had been looking terrible the past couple of days..and the night before he wasn't even moving or eating. Yesterday morning I found him dead...with orange puss coming out of the side of his stomach. I knew there was something going on inside of him. I could just tell he was in pain. I have no idea what it was that killed him though..and I'd like to know if any of you know?
Please don't lecture me on not knowing much about them...it was either this or me letting them die. In my opinion I've done a damn good job so far.
But now, I'm concerned about my other baby degu. He took a nasty fall yesterday. I took him out of his cage for a feeding and (since he's extremely feisty and energetic) he leaped out of my hand (it had to have been atleast 4 or 5 feet from the ground) and he landed on tile. At first I thought he was dead...he looked like he had broken his neck. Then he started to move a little. I moved him to the carpet and he started trying to run to me..but kept falling over and running sideways. After a few minutes he seemed back to normal...,and today he's acting like he was before the fall...he's energetic..he eats very well...he runs around and jumps and plays.
But I just fed him...and I found a little bump on his tummy..right in the center. It's not hard..its very soft..and its like under his skin. It wasn't there yesterday. I just don't know what to do and I can't find anything online. He's only about 2 weeks old. Someone please help me.
Here is a picture of him with the bump
http://i892.photobucket.com/albums/ac126/nschneeberg/bump.jpg

can anyone tell me what this is and what I need to do?

A lump can be a tumor, cyst, abscess or foreign body under the skin. The only way to know is to have a vet look at it.

so, go to a vet and ask how to care more properly and what to do about the bump

We had a very similar situation with our baby degu 5 years ago. The mother wasn't doing very well having given birth to a litter about 10 days earlier. We took her and the two surviving babies to a vet. That proved to be a very expensive visit. One of the babies died at the vet's and the mother died a week later (she was on a regimen of antibiotics and critical care formula). The one surviving baby developed a lump in exactly the same spot as in the photo. It gradually got bigger as he grew and then stabilized to about the size of a quarter. It did not appear to cause him any discomfort at all. We named him Button as it seemed appropriate.

Sadly Button died last night just shy of his 5th birthday. As with many of these small animals, they go quickly, sometimes in a matter of hours after showing the first symptoms of distress. He had a happy life and will be missed.

I'm not saying your situation is the same. Maybe in our case we were just lucky. I've read many degu threads about veternary care and surgery, sometimes with great outcomes but other times not. We love our pets but there is a reasonable limit to what can be done.

I wish you all the best with your little degu.