Whats wrong with my goldfish?

It floats to the top of the water then swims back down but it keeps floating back. I gave it some peas and it was better for a few weeks its doing the same thing again

does it have little white dots on it ?
they could have ick and that could make them just lay there and then just swim away I had some fish and they did the same thing

...more peas?

it sounds like its swim bladder will not deflate! fish have a chamber in their bodies where they trap air to help them ascend, and release air to help them descend. occasionally this chamber malfunctions and wont deflate. then you get just what you have described. unfortunately there is nothing you can do. I am sorry to say, that as far as I know, this condition is fatal. but dont give up on fish because of this expirience. gold fish are usually very hearty fish, and not expensive to keep...or replace if something goes wrong.

...more peas please

yeah, just more peas please

its not easy to give straight answer.if your fish is not suffering from a disses then just check weather your air pumper is working properly or you even could have too many fish in your tank .the point is lack of oxygen brings up fish to the surface to breath.