On May 2 I had my blood drawn around 11am and felt fine. Then 12 hours later I have a huge rash/ red blotches on my arm, near where the needle was. It's not super itchy, it's just puffy and uncomfortable. It's also kinda hard, but feels like there is liquid or something in there. It's almost like a giant bug bite or hive. I don't know if I should just wait until it goes away, or go to the emergency room?