What kind of turtle do i have?

What kind of turtle do i have i cant really tell and i bought him he was $20 kinda a rip off but he wont eat a thing and his shell is getting squishier and squishier cuz he not eating he hasn't eating for bout 2 months now im surprised he alive but HELP ME I DONT WAN HIM TO DIE!!! pics included only 4 all in same photo album: http://i674.photobucket.com/albums/vv106/Kingdomheartsrock/My%20Turtle%20Lucky%20until%20i%20found%20out%20he%20was%20a%20she/P4030026.jpg