By developing "dating" he wanted to say developing dentine,,which is a form of tooth structure under enamel and covers the pulp.
Reason of sensitivity in a new composite restoration can be -
1) high points in the restoration
2 ) some microleakage around the restoration
3) irritation of pulp during cavity preparation or acid etching
What exactly happened in your case can't be said without clinically examining and looking at xrays and the restoration.
Next Steps
visit a nearby dentist
Health Tips
temporary restorations are not meant for long duration as they don't have enough strength to handle the masticatory forces,,avoid eating from that side and get permanent filling done asap
regards