Don't feed it crickets, they wouldn't offer the nutrition that your snake needs.
Sounds like your setup is good. You didn't mention an under tank heater though, what are you using for belly heat? Back heat from a light bulb may not be enough for you snake. Don't keep offering every five days, I would let him relax for 7 days before offering him anything again, sounds like he might be stressed. Have you tried offering rats? Do you live in a state where you can find ASFs? You may have better luck offering ASFs.


EDIT: Just read your last post. Him being active, looking for a way our is a sign of stress which is probably your answer to him refusing food.

what is ASFS and isnt he too small for rats, hes only roughly 18 inches