weird behavior or ill?

Question
My Red ear slider has been leaning to the right side when he is in the water for about 2-3 weeks. Today he looks like he can not get his balance.  His diet is gold fish and aquatic plants.  I gave his tank a good cleaning and new filter 2 weeks ago after this behavior started.  I don't know what to do, and I'm not aware of any reptile vets in the area.
Thanks for your help.

Answer
Lopsided swimming is a key indication of pneumonia, a tough to treat illness in the best of times, and very difficult for the average keeper to fight without a vet's help.

You can try to find a local vet at State Resources section of http://www.austinsturtlepage.com where you can also find some ideas for pneumonia in the Medical Cares section.

You can try to fight it at home by boosting water temps to about 80-85F, offering good UVB lighting (not filtered through glass or plastic), using the fish medicine 'Stress Coat', and giving it good, solid cares and diet on top of that. Try http://www.redearslider.com or Austin's Page listed above for good care and diet articles.

Good luck!