I Got A Lump On My Neck Just Below My

I got a lump on my neck just below my chin. It appears overnight and i felt it hard and painful the next morning. I applied antibiotic ointment the whole day. Next day when I woke up its not that much hard or painful. Would it disappear without any treatment? What may the cause? I have been suffering from mouth ulcers and pimples on my face, so I took this too as a bacterial infection but i am not getting it now.