Suggest Treatment For A Lump On The Foot After An Injury

I dropped a trampoline on my foot about 4 weeks ago. At the time it swelled up a lot so I iced it for about 3 days on and off. It felt really bruised to touch but no bruise came out, it was also very painful to walk on. The swelling has gone down but there is now a quite painful lump on my foot. Please could you advise me on what I should do?