Holly Crap! You're killing him. That's way too high. You'd have to do about 22 water changes @50% each to get it to zero right now. You might as well scoop him up in a bowl and dump that water out. If you have anything in that tank, gravel, decorations... take it all out. Leave it out till you get the filter. Refill that tank with good treated water and 80 degrees. And slowly add a little of that water to his bowl. Just don't shock him. Take a little out then add a little more. Be very careful with this. Float him in the tank to keep him warm while doing this. Do this slowly till you think all the water is replaced in the bowl from the new tank water. I'd say every 15 min. Or so. Add a little take a little. When you get him back in the tank do water changes 2 times a day. Morning and night. 3 gallons will not take long for the ammonia to spike again. When you get the filter make sure you rinse the cartridge off before you use it.