What Causes Painful Lumps Under The Skin Of Abdomen While Having Bladder Cancer?

Hello, I have had lumps that are painful under the skin of my abdomen near the navel area...they are not soft but hard and always painful. No skin discoloration is noticed, but it seems that my skin has gotten itchier since they are there. I have bladder cancer and will have a tumor removed for the fourth time occurrence. I will be having it late next week, but I don t know about these lumps and the pain it comes with and if it will be dangerous to have surgery now. Could these lumps be hernia s or spread of the bladder cancer? Possible blockage of colon? But BM s have been regular all along. What s going on? Can you help me? thanks Gail