Upper Inner Thigh Strain

I ran the Virtual RBC Brooklyn HM last Saturday and after two days off from running I started feeling a bit of a strain in my upper inner thigh area. Last week I ran my usual mileage and the pain would bother me for the first 0.5 mile and then go away. It's over a week later and I still have the nagging pain, which on a scale of 1-10 I'd rate as a 3. It bothers me a bit when I walk but not while biking or sitting. 

Is this something I can run through or should I take time off until it completely heals? 
Also is there anything else I should be doing to help recovery?
Is there anything I should focus on in the future in order to prevent this from happening again in the future as I prepare to start full time marathon training in the next few weeks?

Thank you in advance for any and all thoughts and advice!