Pain/redness On Inside Of Bottom Lip/gums.

Hi, a few weeks ago I had pain between my lower lip and gum (right where the inner lip connects to the gumline) and I noticed that my bottom gums were significantly red in comparison to my pink-colored upper gums. As the pain grew, at first there seemed to be a tiny cluster of white dots and then they disappeared and it felt like there could be a bump on the part that hurt but I couldn t see one. The pain eventually subsided after about a week, week and a half and everything returned to normal. I saw my dentist and he laughed it off saying my gums were a little red but I probably cut it with a potato chip. The pain, redness, and feeling of a bump in the same area have returned. I have had canker sores before but this doesn t look or feel like one. What can this be and why is it reocurring? And what can I do? By the way-- I am 23, female and a smoker.