I have a fleshy sac protruding from my gum below my wisdom tooth. Is it serious?

Hi doctor,

Before a week I noticed a fleshy sac protruding from my back left gum below my wisdom tooth. I do not had pain or discomfort. I decided to rinse my mouth with salt water for few times on that day to see for the disappearance of it. The next day, the sac got smaller but I had a swelling in my neck. I do not had pain in my neck or mouth. But I was able to feel the lymph node with my finger when I titled my neck. After two days, the sac in my mouth was gone. I had pain on the left side of the neck slightly and the lymph node was tighter when I felt it with my fingers. Is this a serious problem or a common one? Please suggest.