What Causes Swelling And Pain On Wrist After A Rosebush Thorn Prick?

Hi, I just slightly pricked the top of my wrist on a rosebush thorn and immediately, unbelievably, it swelled up so fast . The swelling is enormous and I am shocked it is getting so big. I am icing it now but it is not going down and seems to be extending. Any insight into this? It was truly amazing. I didn't even bump the rose bush very hard. It doesn't really hurt just looks terrible and very distorted. Is this a broken blood vessel? Thank you! Anita