Goldfish with prolapsed rectum and prone to swimming upside down

So my fish Cupcake is a Calico Thai Oranda in a 20 gallon tank. She is a sweet fish but a couple months after I got her I did notice her rectum was bulging a bit and did find she had eggs when I noticed her swimming a bit awkwardly. In February the heater died and I have been noticing her swimming upside down more and more. I have removed many decorations and give her broccoli every so often. She seems to do better after a water change but this time she has been upside twice by the dead heater and filter becoming still till I help her out I don’t know if I should be concerned or what I can do to help.

She’s always had one red eye and one blue

I can't tell much from the pictures, a 1 minute video might show more. Upload videos to YouTube, then copy & paste the link here.

If you feed the fish a lot of dry food, it might have air in its intestine and that is causing the fish to float and have trouble keeping upright. The easiest way to test this is to stop feeding dry food for a week and use frozen or live foods instead. If the problem fixes itself when the dry food is removed from the diet, then it is air trapped in the intestine. If this is the case, then only feed dry food a couple of times a week and use frozen or live foods the rest of the time.

If the problem continues when the fish has been off dry food for a week, then it probably has a swim bladder problem. There is no cure for that.

Fantail goldfish and short bodied goldfish have their organs squished up and this makes them more susceptible to internal health issues. Balloon fishes like balloon mollies also have the same problem.

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Depending on the weather, goldfish shouldn't need a heater. However, the fancy varieties do better in water that is above 16C (60F).