In my town there is only one place I know to buy live feeders for my BP, PetCo. They tend to run out of rats quickly:

A few weeks ago I got him a medium rat instead of a small one b/c that's all there was and he is at a size where he should be able to handle it.
All was going normal and then halfway through the rat my BP started struggling and even retracted a few millimeters of the half eaten rat but eventually he got the rat down, but ever since then he runs from rats even small ones, last week he took a mouse no problem, so this week we got him a small rat and still he just ran.

What can I do?
What should I do?

Thank You ,
Kayla