I think i popped my shoulder whilst biking. i was just a tiny little bump. 3 months on i'm still feeling pain should it really take this long to heal?

3 months seems long: A shoulder injury from biking should be evaluated by a sports medicine doctor or an orthopedic doctor if the injury does not heal up quickly. Perhaps a ligament (holding 2 bones together) was damaged. Sometimes there is impingement, where a ligament or bone is pressing on another ligament or muscle. After initial treatment, physical therapy for a few weeks should help regain normal mobility.

Not usually: I agree that physical therapy and antiinflammatories should help, but if not an appropriate injection could help. This could be in your ac joint, which would be different from a typical shoulder injection.