The possible reason for pain while chewing following a dental filling is the slight high point on the filling.
High point is the little excess filling which prevents the tooth to close in proper required position.
Since the dentist has removed the filling and there is temporary filling now, the high point prob is solved.
Another possible reason is that the decay has caused the bacteria to go into the pulp of tooth and you may require a root canal treatment.
Your dentist will analyse that and tell you.
Next Steps
Trust your doctor and ask him/her to explain your doubts. They sure will.
Health Tips
Don’t leave the treatment incomplete.