Help

[Galaxy]

I have a black molly which had a white mark on her side a couple of weeks ago. I treated the tank with an antifungus treatment and hey presto the mark was gone within a couple of days. Last night I noticed that she has now a large swelling in the same area and the skin looks slightly broken. What is this?

 

[WILDER]

It's a swelling and not a bump, does it look like it's filled with fluid, or does it feel hard, just try and feel it on the fish if you can.