Right side, below ear, behind jar is hard knot (gland?)?

On the right side, below my ear but behind my jaw bone there is hard knot. It isn't really sore, only seldom when I touch it. Interestingly enough though, it's sore when I drink any kind of alcohol. Not sure why, but it's been this way for almost a year. The swelling goes down sometimes but comes back (even within a day). What is this???? Any idea?