Is this pain constant or just when you bite down on it?
The crown may be too high (as in too tall) for your bite and its causing the pain. Or it could be a bad fitting crown and its building up either alot of plaque/food in the area, creating discomfort.
How long has it been on for?
Oh wow. Ya, a temporary is just that, a temporary. Any number of things could be going on but I'm guessing that there may be a cavity forming underneath your crown. You're going to need to see a dentist and get it evaluated.
If cost is an issue, you may need to contact your local dental society or find a local dental school to get it treated. Its possible that removing the tooth is the only option if its severely decayed
I have had the temp for about 6 months. Just cant afford it. It is constant pain and relieved a very small amount when I bite down. It seems to get worse when I lay down for an extended period. Thank you very much for your help!