3 month Painted Turtle not well

2 weeks ago this little guy could run away from you as fast as lightning.

if you held him in your hand, keep a close eye and catch him as his tries to fall off.
I went on vacation for just a week and had someone feed/watch over him
But the day that i came back i took him out of his 10gallon tank and it seemed as if he barely knew how to walk...he was having trouble pull him self up to crawl away..Hes only about 3-4inches wide. tiny little guy. But he does seem to be growing a bit.
as a baby could his shell be too heavy for him? should i let him crawl out of the water more to help him?

Thanks hope you can help .