The headset can compress (dent) the tissue that it sits directly on. This will cause the tissue around the "dent" to swell up and feel soft.
I'd keep that in mind and maybe switch to a lighter weight set (or switch to some buds with a mic?) until you get into the doctor. But, chances are it is just the headset causing pressure.
Well, I have wear headphones (head-set style, not earbuds) a lot recently. o:
Silly question but are you a gamer or do you wear a headset for any length of time?
That could be a culprit if you do :)
Did I seriously just misspell that as "Spot spot"?
*facepalms*