Longnose Hawkfish broken???

[zum14]

So a few days ago I noticed my longnose hawk hanging out on the sand of my tank on his side, uh oh not good. Took a look, color was awesome, didnt really look like he was breathing hard. Got close, he flipped up and propped himself up and looked at me as if he was playing possum. I checked him over and noticed the top half of his front fin on the left side was clipped by something, not sure what did it, maybe one of those crabs I found or my six line as ive seen them go at it before. He still had the bottom of the fin they use for propping themselves up but the soft top part is gone. So he still ate and sort of swam a little off but my guess was from not having a full paddle on the one side was messing him up a bit. So at that point he was propping himself back up on my corals and such and moving around I thought he was going to pull through. Tonight looked pretty bad. Turned off all the pumps for feeding. He was perched on a coral. Dropped some food in and his head turned towards it. He took off and well the best way I can describe it is it looks like hes not using his tail anymore to swim. He seemed to be earlier but not tonight(maybe yesterday too). So with one bum fin and not using his tail hes looking really awkward trying to swim, going over backwards, doing circles, He took a couple pieces of food but shortly started a decent to the bottom where he rested, the next time I looked at the tank he was back up on the coral. He also seems to be breathing fairly hard today, harder then normal. I did a large water change this weekend but both the cardinal and 6 line look stellar, just the hawkfish having problems. Any ideas? Im a little worried about this now, I thought he was going to pull through this. Thanks for any help anyone can offer.