My daughter fell from a tree a few months ago and strained her foot (X-Ray showed no bone breaks). Her gait is still a bit off. Should I be concerned?

Possibly. An initial x-ray of the foot at the time of injury will not always show a hairline fracture of a foot bone. If there is continued pain after 2 weeks, a repeat xray may reveal a fracture that wasn't evident on the initial exam. An MRI is sometimes needed to evaluate subtle fractures. An orthopedist evaluation of your daughter's foot injury may be helpful.