10 gallon, planted
You only need 1 of the 3 options ibgave you. You can get them at Walmart, petsmart or Petco. FYI: Do not buy test strips to analyze your GH and KH. They are not accurate and a waste of money.If that is what your tap is popping for test your ammonia in your tank now. If it is above 0.25 do a 20% water change and get to the store and get conditioner and put it directly into your tank based on 10 gallon dosage.
Mallory, I pulled up some products you can get:
1. API Tap Water Conditoner which is just a Dechlorinator that removes ammonia and such plus heavy metals.
2. API Stress Coat plus, it does the same as above and more. I picked this because your fish is probably suffering ammonia poisoning.
3. Tetra AquaSafe Plus Aquarium Dechlorinator Water Conditoner, this similar to the API Stress Coat.
The first product I listed is cheaper and will get your water out of danger. You must act fast. Water changes are not going to help as ammonia is in your tap from the well. Crap, it doesn't even matter if you get cheap Dechlorinator for Bettas. And again, if you can afford it try to the API GH KH Kit. GH & KH are advance Water information test not to be expect to be understood for beginners but they matter and I can explain what they mean when I have the readings. There is not anything else you need for now.