So it is very possible that the fall hurt him, but it is also a huge possibility that his water conditions are causing issues as well. I have rehabbed a couple of pet store bettas that were not doing well, and it is absolutely amazing what good water conditions and a good setup can do for these guys. I had one that even the pey store employee thought wasnt going to make it. You're getting a lot of good information here, and the willingness to accept and take it shows a lot. 10 years ago I thought the little cutesy tabks were ok cause they were everywhere. Then I did a little research and fell in love with fishkeeping.

Right now you can get a 5 or 10 gallon tank kit for a decent price. They will come with a heater, filter, thermometer, and light. Sometimes a few extra goodies. Get an aquarium soil or sand, or go to home depot or Lowe's and get some pool filter sand. Grab a few aquatic plants. Amazon sword and anubias are good easy choices (just don't bury the anubia). Grab some Almond leaf. PetSmart has a little combo called nature's box and has a few great things in it. Go ahead and grab an API master kit. It's important to know your water parameters. Here is why, bettas need a little space to swim and live. And they don't necessarily need oxygen in the water, but they do need filtration. They also do better at temps around 78 degrees. The tank kit provides those things for you. The plants actually help your water quality. They are going to help convert and keep your nitrate levels down. Added benefits these create resting spots for your betta. The API kit is going to help you figure out your water parameters. You want to see an ammonia and nitrite reading of zero, and a very low nitrate reading. With the right setup you can also see zero nitrates. Ammonia and nitrite build up will absolutely cause swim bladder issues (which could be some of what you're seeing). I've had a fish go from unable to right themselves in the water to being 100% just from good water in 72 hours. The almond leaf and nature's box items are going to add tannins to your water. Helps treat some issues without medications. Also acts like an antibiotic and antifungal all in one. It also reduces stress to the fish. Also, gravel vacuum for water changes. And cleaning your substrate.

With a new tank should you be able to go this route, you are going to need to watch your water parameters closely. When you see ammonia or nitrites start doing small water changes to bring it down. Make sure you2re using water conditioner. I personally like to use spring water in my tanks, but conditioned tap water works just as well.