Force fed after 4 weeks? Before trying a live mouse?
Houseing two in one enclosure?
Dont take this the wrong way because its only one opinion and your not going to like it.

Put the poor guy In a tub with nothing but water, hides and hotspot.
Leave him alone except for feeding. Try frozen if you want then try live mice.

Who suggested force feeding? Petco?
No wonder he won't eat.

Im newish and only basing this off the small information I've acquired from a handfull of books and the masses around the net.

Force feeding? 4 weeks. Hrm