How Long Does Dermatitis Take To Cure?

Hi Dr Andrew Rynne. My child, Emily is suffering from dermatitis. It is currently mild but I m concerned that it will get more severe. I have a few inquiries. 1. Will it be prudent for her to not go to school? 2. Approximately how long would it take for her to recover? 3.Do we absolutely need to see a doctor? Thanks, Jane