Urgent help needed with my fantail goldfish!?

There is unfortunately no way your tank cycled in 4 days. It takes weeks. And the only way you can tell that you are cycled is a 0 ammonia reading.Along with 0 nitrites. And nitrates rising which are the good ones as long as you keep them low with water changes. A biorb is not for goldfish you need a larger tank. And you need to be doing water changes every day as long as you are showing ammonia and nitrites. He might improve if you keep up the water changes. Go to www.kokosgoldfish.invisionzone.com for help they are great there.