I had this happen to my ankle after surgery. It was constantly red and purple looking, and I saw these white pieces of what looked like string coming out of the scar. I tried pulling on one, and it jerked out covered in blood and hurt like hell. I had no idea it was INSIDE my body! Freaky experience. After that, I would just get finger nail clippers to get as close to my skin as possible and clip them. I had this happen with stiff, black thread, and blue softer threads. You can still visably see some of them under the skin.
Whoever sold these as disolvable, sold a lemon of a product! Good luck. It sounds like yours is working it's way out and creating a hole where it is trying to come through. I had this too, and it took several weeks to heal with constant neosporin and band-aids. Let me know how it works out.