A. It's most likely a cyst, or possibly a swollen gland. It might signify a minor infection, but after two ER doctors have seen it, I'm certain it's nothing to worry about.
B. Just relax. Frankly, I'd be amazed if this turned out to be anything serious. But let's say for arguments sake that it is, then what good is worrying about it doing you? Three or four days are not going to make a different in the scheme of things. Just take it easy and wait to see what the doctor says.