Hurt Angelfish emergency

Question
I am very new at owning a fish tank so please bear with me. I set up a 29 gallon tank in January. I later added a small school of 6 cardinal tetras, during March. Everything was doing well. So I went and got 4 cory cats to manage the uneaten food. I also got 2 small angel fish. Before adding the fish to the tank I did a water change (since it was the end of the week). My tank is high up so I have to use a small step ladder to pour the water in. My boyfriend was helping me. He was adding the water when he lost his balance. He slipped and in an attempt to stop he fall he stepped onto the small coffee table next to the tank. This is where the two fish bags were sitting. He stepped on the bag with the angel fish in it. The bag popped and the water started spilling out. I panicked, grabbed the bag with the two angel fish still inside and put them into the tank.... my boyfriend was ok and so was the cory cats. The black angel fish acted totally ok. In fact he started trying to eat the floating stuff that was stirred up from the water change. But the stripped angel fish hid at the bottom of the tank. He kept moving some but stayed hidden in the back of the tank. The next morning he seemed fine. He was at the top and in the front. But later that day I couldn't find him. It took me hours to spot him out. He was once again at the bottom in the back. the next day I separated him into a little travel carrier tank, it is hanging inside of the 29 gallon tank. Now I can observe him better, he is no longer swimming straight. He keeps laying onto the ground to rest then starts swimming again and swims in circles and spirals and upside down. He seems very weak at times but strong at others. He goes to the surface sometimes and hangs out there. I later put tin foil (with holes punched into it) onto the top of the tank to provide some darkness. He responded well to this. He seems a little more active but still acts hurt. I added some food but he didn't eat. I am planning on adding some aquarium salt and "stress zyme" to help his immune system and prevent any infection. Other than that I don't know what to do. If you know of anything please let me know. I just want to save him if I can. I really really want him to live, he is a lively fish and seems to want to live. I just don't know what to do to help him.

Answer
Okay, first off, if there is no air in the travel tank, he's going to die.  The spinning is dying.  There is lack of oxygen.  I recommend putting him back into the main tank and just keeping an eye on him.  Do not remove him.

Heat is essential.  I know travel tanks have no heat...he's got to have a heated tank to 80 right now.  

Heat, clean water (you are doing monthly water changes of 25%, right?), spotless filter cartridges and putting him in a very well aerated tank are my recommendations.  Aeration will help him recouperate.

Gosh, I hope he gets better.  Please write me and let me know if this has helped and his condition.  I hope it's not too late.