Shin splints vs. something else?

Hi! I recently developed mild pain on the front/lateral side of my right shin–– it started very faintly on Saturday after a long run, then went away, and then returned during and after a medium run on Monday morning. The pain is only 3ish/10 but has persisted despite taking the past 2 days off of running. I’m concerned about a bone stress injury (e.g. a stress fracture/reaction) so I’m wondering if anyone has advice on how to differentiate shin splints vs. stress reaction (or stress fracture)? And how to heal quickly to get back to running soon? I’ve been base-building (25-35 miles/week) and was planning to start a winter training block for a spring marathon in a couple of weeks but want to make sure everything is fine before then. TIA!