Oh no! I'm sorry you're in pain sister!
You may (or may not) see the actually "plug" it would look kinda like string cheese. There may be a bit of tenderness (from the excessive pumping and hand expression) but a definite relief of some sort.
Let us know if things worsen or if you begin to get red, swelling or any flulike symptoms
oh no!!! hope this has resolved by now for you.... but my two cents are that i NEVER have had a plug come out in a manner that was visible (i keep on hearing about the 'cheesy plug' lol!) however it is likely because the baby unplugged it during nursing after much compression and moist heat (massages in shower, etc). and the soreness and swelling can take some time to resolve, i have found.
mastitis is AWFUL -- i truly hope this resolves for you, hun. big hugs.