Hello,
The pain behind the last tooth might be due to the eruption of that tooth or food getting stuck under the gum there.
The main point of concern in the picture is multiple decayed teeth in the 7yr old. These teeth have to be saved for the next 4-5yrs, so please visit a dentist d get them filled.
Sometimes the pain from decayed teeth may radiate to other regions also.
Next Steps
1.Get the necessary treatment done for decayed teeth
2. Maintain good oral hygiene - brush twice a day and rinse after meals
Health Tips
do not neglect decayed milk teeth