It looks like you might have swallowed a very small piece of bone which might have minimally injured your esophagus ( food pipe) while swallowing..
It looks like the pain in the back could be due to that.... however if the pain persists you might require an upper GI endoscopy just to be sure ....
Next Steps
wait and watch for symptoms such as - persistent pain , vomiting of blood, difficulty/ pain during swallowing...blood in stools
...if they occur then visit a surgeon immediately
Health Tips
have plenty of fluids