Weird bump on my arm?

Big Bump on my arm came out of on where when i was sitting on my bed?

• It happened last night, All of a sudden my forearm itched a little, an i felt this really big bump, over the next 10minutes my entire arm had the feeling when your foot falls asleep. Woke up this morning and the bump is still the same size on my forearm. The bump isn't itching very much, but it feels as if something is tickling me inside the bump. I don't have any bite marks. Anyone ever experience anything like this before that can tell me what this is?(the bump is the size of a 50 cent piece coin and rises off my skin about 1-2 centimeters, and its red.)

• Answer:

  Never had anything like that before, although I've experienced smaller bumps on my skin and itching on my lip, my lip went swollen for a few minutes once and then went back too normal o.o I'd go see a doctor, we won't know anything and if theres a Dr here they can't help you without seeing it for themselves.