Eating problem: Could a bigger terrarium help?

[Simland]

Sorry if this is a double posting. It doesn't look like the first time worked.

I have a snake that I've had for a while. For the first year, he was a regular eater, but since then he has become a very irregular eater with long bouts of eating next to nothing and losing weight. I've tried several things, and, now, with its elevated basking spot, the air temp above the basking spot can reach 29C (84.2F), while the cool side stays around 23C(73.4F) on a relatively cool fall day. Yet, in the past month it hasn't eaten much. It stubbornly refuses earth worms and only eats pinkies once in a while.

One of my theories is that the night temps are too cool (around 20C [68F]), could that be it?

But I'm also wondering if it could be bored with its 30 inch / 12 inch terrarium.

So, my dilemma at the moment is this: I recently purchased a terrarium for my new garter. This terrarium is 36 inch / 12 inc. Should I give it to my anorexic garter and put my new garter in the 30 inch one? My new snake is the bigger of the two; enough so that the larger terrarium seems like the better fit, to me.

Do you guys think the additional space would make a difference in the eating habits of my difficult garter?

[Qwerty3159]

The extra space would probably be appreciated but six inches isn't a lot of difference and I don't think it'll make an impact on feeding.
I'm dealing with a checkered who does the same thing right now.

[guidofatherof5]

Could be internal parasites.