You most likely have a Colles fracture. This is a fracture of the distal radius at the wrist. Most of these fractures are displaced, and need reduction before immobilizing them. Even if not displaced, if not properly immobilized they can displace during the first two weeks post fracture, as that is the period of bone adsorption.
The wrist is a complex area and there are a number of fractures that can occur. Scaphoid fractures are notorious for non union, if not handled properly, and will cause life long disability. Any displaced fracture not reduced, will cause lifelong disability also.
In addition, radial fractures frequently are associated with ulnar fractures also.
The bottom line is that X-ray of your forearm is mandatory to asses the situation, and see what intervention may be necessary. You absolutely need medical attention, and tonight, considering you may have an unstable fracture that will worsen if not attended to correctly.