The "hot spot" to me looks like direct sunlight, while most of the rest of the photo seems to be in the shade. Here are some possible fixes:
1. When shooting in the middle of a clear day, have your subject's back to the sun. This will prevent hot spots and harsh shadows.
2. Use "fill flash". But I don't think it would have completely solved the problem in this situation.
3. Make sure your subject is completely in the shade.
I think any time you have some part of a persons face with direct sunlight and another part in shade/shadows the camera is going to have a hard time and will either "blow out" the bright parts or underexpose anything that's not being hit by direct sunlight.