What specifically though, is it a three day split? are you beating the same body parts 3 days over on top of boxing.

What ever you doing it's likely that you aren't allowing yourself adaquate recovery... either from poor nutrition or poor training planning and lack of rest.

If you're doing the same thing over and over and need feeding yourself properly then expect to stall and then regress... anything but develop.

Gives us a typical monday to sunday mate, I haven't got enough to even speculate on...