One time, I was able to do this with a photo I too just using the camera. The next time I tried it, the doodle option was gone from the edit menu of Facebook sharing. Now I only find it for photos taken within Facebook. I know I was able to do it straight from the camera before. What gives?!
Addendum: With some experimentation, I figured out that you can't doodle on screencaps for some reason.
Addendum: With some experimentation, I figured out that you can't doodle on screencaps for some reason.