When I got my baby BP he hadn't eaten for 2 weeks, and it took 10 days for him to eat for me. In an earlier post you said it has only been 2 weeks since he last ate? Losing 22grams seems like a lot (and I'm not an expert at any rate, so it might be a lot). But try not to worry yourself *too* much! That will only stress you out more, which I'm sure doesn't help the situation.
I don't have anything else to offer, unfortunately, as my BP already had 3 f/t feedings prior to me (All I did was let the thawed pinky sit in a warm cup of water beside the vive for a few minutes to arouse my BP... then placed it inside with tongs - he wouldn't strike it - He ate it butt-first, without curling around it).
Strange things happen. You just never know.
Good luck!!