Trying to feed him several times a day is going to stress any reptile out. Heck, my corn wouldn't even eat if I bugged her constantly with a meal. So don't do that anymore.

In fact, ignore your snake for a bit. Stop fussing. Stop looking in. Stop bugging your little guy. Let him settle. If you feel his tub is too big, crumble up some paper and put it in there to fill the 'space' he's feeling. I did this for my little BP hatchling and he started to calmly explore (whereas before he would hide constantly).

How are you heating up the rat fuzzies?

Honestly, I would leave your snake alone until he stops crusing like he's stressed. Leave him alone for now. Ignore him. Wait until he isn't cruising anymore (a sign of stress). Once he calms down, offer him a rat by thawing it very very nice and warm (I use warm water. Works every time). Then put it in there on the warm side. If he doesn't strike, leave the rat in there overnight. If he doesn't eat it, remove it in the morning and try again in 5-7 days. The more you try to force him to eat, the more he's going to be stressed at the idea of eating.

Also: You shouldn't need reptibark for a young ball python. You can keep him on whatever substrate you want, as long as you are providing enough hides, a secure location, and get rid of all that 'open' space in his enclosure.