For ammonia poisoning the best treatment is just clean warm water. To help your Betta's immune-system you could raise the temp in your tank to 80F. To help boost his immune-system you can soak his food in some garlic juice. Getting him a good quality food is also very important. I did not know this myself for a very long time, but Bettas being carnivores need special foods. The Betta pellets from New Life Spectrum are made with good ingredients. And don't feed him freeze dried blood worms, they can cause bloat, better are the frozen bloodworms. You may have to ask for them at your LFS if you can't find them, they are kept in freezers.
As to your question, I have no experience with the products you added, you might need to check what could contain anything to raise your pH. You need to be very careful getting your Betta's tank water back down to the levels of your tap water. Making daily small changes will help you there. 25% sound a little too much for me, I would rather go with 10% at each change to give your Betta time to adjust, especially after still recuperating from Ammonia poisoning and the different products that he was introduced to.
How come your Betta had ammonia poisoning to start with, did you just buy him from a store where he was ill maintained in his little cup? Is the tank he is in now a cycled tank? Is there something in the substrate that could have raised your pH?