Oh and the answer is no, it can't heal that quickly.
I was in a car accident a few months back and had to be VERY insistent with my doctor that something wasn't "right" in my wrist, even after negative x-rays. He finally put me in a cast and the fracture showed up on x-rays a couple weeks later as it started to ossify. If you aren't confident in your specialist, don't hesitate to switch. I had to do that too! Scaphoid fractures are a pain, don't mess around with them and take care of yourself. Good luck!
Often, Scaphoid fractures are non-displaced, and do not show on the first set of xrays. Therefore, if there is a suspicion of a scaphoid fracture, the patient is usuallu immobilized for two weeks even if the exrays are positive. They are thern rexrayed. If the xrays are still negative, but the patient still has pain, an MRI or CT scan can be definitive.