tampon troubles

I kept a tampon in longer than I usually do but my period is close to ending. I had to work for someone else who went home sick (so I'm not that stupid, I didn't know that I would need another tampon). I took it out after I used it for like 8 hours and now I'm kinda itchy (which usually happens at the end of my cycle but not this bad) and a bit sore. Any ideas?