For about two months, my betta has been growing a lump on her side. Initially I thought it was a tumor, but it appears to be completely fluid. Maybe it's a cyst? She is a whitish/pink color and is mildly transparent so I can see the outlines of her organs and the fluid is not inside any organs. There isn't an overall fluid build up in her abdomen like bettas normally have when they have dropsy, so I highly doubt that's what it is. The fluid build up is in a concentrated area. Her scales are raised, but only on the lump. She does have some redness on her scales that wasn't there before. And she is breathing heavily. Other than that, her activity and appetite is completely normal.
I have considered using a syringe to drain the fluid, but I've read posts about other people doing that and it seems to result in death half the time.
She is in a divided 10 g tank with 1 other betta. It's 76 degrees F and filtered. I do a 30% water change every week. She eats two pellets twice a day, but I cut back to two pellets once a day to help with her bloating.
This started as a small lump forming on her side and is now a very large lump with additional fluid build up on her other side. I'll post previous pictures I took when i first noticed and then again after a few weeks passed.
Please tell me what I can do to help her.