This is not your redfoots or one of your Russians right? Is it a water turtle or a semiwater turtle? How old is it? How long have you had it? What kind is it? Tell us how your caring for it please.... size of enclosure, water depth, water temp, basking temp, diet, has it started acting different, and such all are important to know in order to give you any help at all.
I went back and read your "Introduction" and I see in your signature that you may be talking about a baby sulcata. Did you read the "important threads" at the top of the sulcata section? These threads will give you all the information you need to set your baby up properly.
If your baby tortoise isn't warm enough, you run the chance of him getting a respiratory infection, which usually means bubbles out the nose.
Please read the "important threads" and make sure your baby is warm enough. A lot of times, just upping the temperature in the habitat will make the bubbles go away. But you don't want it too hot either. So, read, read, read!!!