do i need to take my turtle to the vet

by donna
(england)

i have yellow bellied turtles and 1 of them is ill she not moving around as much and her neck gone abit white she is staying under the water trying to dig a hole in the corner and her shell it flaking but its still hard i thing she is aroung about 4/5 yrs old and she is in the takn with a male the tank is 2' up. 2'across. 1' back. pleace can u help me