The large lump does it look like a cauliflower or a cluster of berries.
What colour is the lump?
Is the lump hard or soft like filled with fluid.
could you recomend a product, and as for it bursting he's alone in his tank. thanks for your help.All you can do is try a bacterial med just to make sure it isn't a tumour.
Best to issolate though as lump can burst and infect the tank.
Good luck.