Does anyone have an extra Swelling Potion?

Hello, like some others I've been stuck on book 2 chapter 11 for months. Despite trying a ridiculous amount of times, it seems like I would get a Troll mark in my potions OWLs. I really don't like to beg like that, but if anyone had an extra potion it would be extremely nice. My name there is FrogNimbus135.

Again, I am REALLY sorry (like canadian sorry...) but I just suck so much at this. :S

Thanks!