swelling of gum

I have had swelling on my lower left gums since November.  The swelling is hard but has gone down some since November.  It is swollen on both the outer and inner part of one of my back molars.  A few times it has ached, generally because I have been messing with it, and sometimes the molar is very sensitive, especially when I bite on something hard.  Normally, it is painless and never bothers me.  Any ideas.  I finally am seeing the dentist in two weeks.

[Jerome Tsang, DDS]

Most likely an abscess of some sort I would imagine.  If the symptoms worsen, I'd go immediately to the dentist or the ER.