Infection or irritation from temp stitches?

[Jwood]

Had an impacted wisdom tooth and the tooth in from of it extracted 7 days ago. Thought it was healing ok. Then today, one of the temporary stitches fell out, well, I then rinse it well with salt water, like 30 mins later it started hurting, and ever since, so I looked at it in mirror and noticed a very dark pink streak from the stitch hole and down the gum line, is it infected or irritated? Need I worry? Advice? Please and thank you.