Jumping Gar, new here!

Well I guess I should have posted in the intro thread first, but I'll start here real quick. I have a spotted gar, temporarily homed in a 55 gal while another tank is being set up, hes been in there for close to a year but I have invested in a 125g for the time being. At any rate, two nights ago I went to take my dog out and the poor guy was lying on the carpet about 10 feet away from the tank. he's about 12-13 inches long and was extremely healthy until then. Today, I noticed hes not able to hang out toward the bottom of the tank, and keeps floating upwards, I dont understand why. He was only out of the tank for an estimated 1-2 hours max. Another thing, is that I can see a bit of red blood like substance near his back fin and under some of his scales, if you will. Now he just keeps hanging out in one corner of the tank and doesn't move too much, and his back is exposed to the air pocket up at the top of the tank. anything that I can do to help his slime coat?? I searched online and found the forum with some other people having issues with their gar's jumping as well, so that's why I'm here! (Also have a Malawi Cichlid set up too) Seems like a very informative forum, I plan to stick around and shed my advice I have as well as gain some new knowledge!! Thanks all for reading and I appreciate the input!!!

Edit--

Also, it seems as if when he does attempt to swim, his nose stays down, and tail keeps wanting to go up towards the top, hes fighting hard but can't seem to get to the bottom or to food. His back is still being exposed to the air, getting me really worried. Thanks for the help in advance, I'd really appreciate it! I don't wanna lose him!!