For the past 3-4 weeks I have developed a brownish hole in my gums. To be honest it looks like I had a tooth pulled but I have never had one pulled. It's not painless but it's not unbearable yet but it is getting worse and seems to be sinking in under that last tooth. If I touch my tongue to the hole it's has a nasty taste to it. And when I brush my teeth it bleeds and become a little sore. I have never had a tooth pulled or wisdom teeth removed. I have had some major sinus problems the past 2 years and I am smoker. I try to brush my teeth 2 times a day but sometimes it's just one. Also I had ovarian cancer as a child. So what could this hole be and what should I do about it?