There are a number of possibilities, it could be simple swelling from irritation or a bite from some insect/bug, could be a cyst, etc. Though I really wouldn't worry about it until you know exactly what it is. Don't stress about it, just get the appointment made with your doctor. It's most likely nothing serious.
I will get there asap a little nervous tho :|
any ideas to what it might be?
You need to make an appointment with your doctor... Good luck