I think I stepped on a stinger or something?

I don't really know what it is... it's red-brown and kinda long. It's right under my big toe but there's an area next to it that is swelling and hurts more than the actual place where it went in. I don't think it's a splinter, as I was in the grass and it seems too long. The thing is, I didn't have any tweezers for a while and I couldn't pick it with my nails so it's been in my foot for a few hours. I can't get it out now, I've been trying for the past 15 minutes. So should I just leave it, take some Advil, and buck up? Or what?