I have had lower back pain for 3 months. I came off my motorbike at slow speed in january. I am also a keen runner. Can still run.?

Probably. First, back pain after an accident that persists for 3 months should be evaluated by a doctor. If you get the green light after that evaluation, it is okay to return to running. Start slowly. If you experience no increase in pain, add volume and intensity in a common sense way. Massage, manual release techniques, body work, etc may help work out persistent complaints. Improve your core.