Having headaches that only last for a few seconds that come and go?

I’m 4 weeks out now from a mild concussion, light sensitivity is gone; loud noise sensitivity gone; literally everything gone except having little headaches that are literally .4/10 that last for a few seconds. Generally I get them a few times a day, and never for more than 12-15 seconds, most of them being less. They aren’t with exertion and I’ve went back to sports practice and lifting. My doctor said this might be normal for 2-3 more weeks. Thoughts?