Louise,

Sometimes when a tooth is fractured it can hurt only after it has been chewed on or annoyed in some way and then the pain may or may not linger ... even sometimes during brushing your teeth it could hurt and then stop. If you grind your teeth at night, the tooth may only hurt during the day and may or may not get progressively worse. Or if you grind during the day, not a night, the tooth may get progressively more painful throughout the day and then calm down during your sleep. Other times, it can hurt less frequently because it has to be moved in a certain way to be aggravated. Sometimes the pain is mostly temperature sensitivity. It all depends on where the fracture is, how large it is and how your teeth occlude together.

The swelling is actually more of a concern than the pain. Does it stay swollen 24 hours a day or swell up after you are awake for awhile? Also, are you taking pain meds before you go to sleep or anything like a muscle relaxer at night?

I am still wondering why the dentist deep scaled the premolar. That is usually done if a problem with the gum, such as in a deep pocket, is suspected. Otherwise it can add insult to injury more so than if not done at all.

Ask this dentist to take an xray at a different angle. It's called bisecting. Perhaps the problem is not being picked up on the xray because they keep taking them from the same angle. Just ask... "could you take this xray from a different angle than the usual straight on to see if anything shows up from that perspective?" Sometimes assistants don't know what bisecting means :/
Also, if the xray is digital, ask them to send you a copy to your email and then you may be able to post it here.

Let me know....
Bryanna