After reading your query I can make out that you hae the cystic swelling known as "EPULIS" over the left gum.
It is a benign swelling which recedes by itself and no treatment is required in maximal cases. I advise you to not pinch or pop the area otherwise these areas are very prone for getting secondary infection. Keep your oral hygiene
on best of the side so that there should no be any chance of infection in the same.