Plavix? Did someone prescribe it?
Doesn't Plavix act like an NSAID, making your platelets sticky? It's probably not safe to be taking Plavix for more than a few days if you're taking Warfarin.
If it was me, I'd try and find something else for the pain (if there IS anything else that works). I don't think Plavix is safe if you take Warfarin. I'd hate to learn that your 'sore throat' had something to do with bleeding in your throat (my throat is often tender if I'm snoring for very long - if my capillaries bled when I irritated my throat, it could make my throat REALLY sore).
One of the issues with warfarin that they don't talk about is that you usually have to avoid NSAIDs or NSAID-like medications, so there's not a lot that is available for pain. I've read that ketoprofen - unfortunately not covered by most insurance and pretty expensive - is perhaps the only NSAID that can help with pain and not mess much with the platelets.
If I were you, I'd check with a doctor about the safety of taking Plavix while you're on warfarin, and see if she may be able to suggest something else.