Bam Margera going to rehab has a celeb boxing promoter in a tough spot -- he's looking to get back the dough he just fronted Bam to ref a high profile match.
Damon Feldman, the promoter putting on a bout featuring the infamous Bagel Boss, tells TMZ ... Bam got half of his fee up front -- a cool $2,500 -- after signing a deal last week agreeing to be a ref. The deal called for Bam to get another $2,500 after the event. Damon says he hopes Bam gets better soon, and he won't won't hold the "Jackass" star to his contract.