Surgery scars/stitches and healing

I had a breast reduction in 2012. Things went great, and I healed up nicely. I've had a small lump under one of my scars that I've figured was just an old stitch that would eventually dissolve.. but now I've been itching under my skin and swelling where the old stitch is. I also feel it poke me. It's a pretty sharp pain.

Has anyone else had this problem with old scars? Do you think the stitch is just finally starting to move around and will hopefully dissolve soon?

I plan on going to the doctor, but I was curious if anybody else experienced this with their scars.