Painter Turtle- Not using back right leg

Question
I have a painter turtle that is not quite a year old.  He has just started not using his back right leg and I noticed a lump between his upper and lower shell by that leg.  Any thoughts as to what this is and if it is serious?  He still eats well.  He is in a 10 gallon aquarium right now.  We feed him crickets and wax worms.  We cover the crickets in calcium powder so he does get calcium in his diet.  Thank you for your help!

Answer
I cannot be sure of what this is, but my guess is that it is not good news. You may want to have it looked at by a vet, or at least ask about it on a site like http://www.turtleforum.com

It sounds like an abscess or possible injury that is affecting the nerves.

(By the way- covering the crickets in powder just lets the water wash the powder off. 'Gut loading' works better.)

Try http://www.austinsturtlepage.com for more ideas.