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Since it's not longer so big, I don't think you need to go to the ER.
You likely had an abscess of a sub-urethral cyst. Since it's drained, nature took care of what the urologist would have done, which is to open and drain it.
Now the condition is more chronic. I would keep your appointment to see the urologist. If you still have a cyst, it can likely be removed fairly easily.
In the meantime, it would be best to soak in warm water with epsom salts. That will keep the area clean , be soothing and healing. Best wishes.