I have a build up of callus on my big toe. lately, it has started to be a little painful. now there's bruising(?) around my toe. what should i do?

Callus Removal: Because the thickness of the callus causes pressure, reducing the overgrown tissue by soaking the feet in warm water and filing down the callus with a pumice stone to smooth down the thick tissue may be helpful.In severe cases, podiatrists may use a device called a sterile surgical blade to remove the outer layers of thickened skin.

See Podiatrist: To find out why callus is forming. Most likely a biomechanical cause. Then in addition to shaving callus, the cause can be addressed.

Depends on the cause: Many things can cause calluses. Some reasons that one may develop a callus include: viral infections (warts), friction, pressure, repedetive trauma, and a limitation of joint motion. Some genetic conditions may also cause people to develop calluses on the hands and the feet. Treatment depends on the cause of the problem. Have it evaluated by a professional and get the appropriate treatment.