Lump on instep

I have a good sized lump on my instep/arch. When pressed, it hurts a little. I have a smaller one on the other foot, as well. I don't know how long i have had it but it must have grown bigger over the summer. I walk a lot with good sneakers over all types of terrain. I don't know if that could mean anything. It could be a cyst. What do you think. I probably will make an appointment with a podiatrist.