I posted a thread about my new Betta about a week ago, as he was floating strangely and wouldn't eat. Since no one answered and his symptoms went away, I didn't treat him for anything. He resumed eating and swimming like normal and seemed healthy. Today, I did a 100% water change, rinsed everything off, and added a couple live plants to his tank. I used water conditioner and let him float for 20 minutes before placing him in.
As soon as I placed Bird in the tank, he freaked out and started swimming on his side and then buried himself under the gravel. I put him back into the cup with a lowered water level and he continued to swim sideways and freak out.
I'm so scared. What is this? What can I do to help him?
Video of how he was swimming: http://youtu.be/a9QRq7VHK0U