Runner w/ lower leg pain

I’ve had this pain in my lower leg (front to front-outside) for 3 weeks now, it doesn’t hurt at all when I’m sitting, only a little sore when walking. But it’s sore if I run, anywhere from just under the knee down to my ankle, which is feeling very weak.

If anyone’s got any opinions on what it might be, please respond. If it’s due to a tight calf (my suspicion, but I’m clearly no genius here), would a sports massage help?

More info: marathon in 1 week. I’ve already adjusted my goal pace down, I’m just wondering if there’s some way to hasten the healing.

Thanks for any info —
Neal.