Hello ardo950, welcome to the forum!
Can you post a picture of this growth?
Do you know how many gallons the bio orb is? What kind of filtration? Goldfish produce a lot of waste, their waist can quickly become a problem in smaller tanks. Many goldfish fall ill to ammonia and nitrite poisoning, not saying that is what is wrong with your fish, but extra clean water will help in the healing process.
If you do not have a water test kit, the liquid API freshwater testing kit would be a good one to buy. Most fish stores will test for free, but I find having a test kit at home handy. Any time I see a fish with signs of illness, the first thing I do is test the water.