Lump and Snezzing

Question
My rat has a lump under his chest, I've only recently noticed this but he's also been snezzing alot. I have two (brothers) and the other is perfectly fine.

Answer
Hi Jill

How long has he had the lump and did it come up fast, like out of nowhere, or did it take a while to grow?  

Is there fur on it?

Is there a scab or a hole in it?

Is he eating and drinking good and still full of energy?

How old is he?

Sorry to ask so many things at once but in order to properly diagnose him I need to know a few things since I of course cannot see him in person.

Please let me know

Thanks


Sandra