Sometimes working on a tooth can agitate it and it takes a while to settle down. Try applying sensodyne toothpaste (smear over with finger) over the tooth after cleaning, last thing at night, then no eating/drinking, allowing it to "soak into" the tooth.
To protect the nerve a lining is placed at the bottom of the cavity prior to placing the filling to insulate it, if this isn't done or isn't thick enough the filling will transfer hot and cold down to the nerve causing pain/sensitivity.
Sometimes the new filling is that much deeper than the old one that it traumatises the nerve causing it to play up, it may settle or the trauma may be too much that the nerve dies. The tooth will then be painfree, but sooner or later that dead tissue within the tooth will become ifected and WHAM, raging tooth ache/abcess etc. In this case the tooth needs to either have root canal treatment where the dead tissue id removed from within the tooth then restored, or if you don't want to go down that route the whole tooth can be removed.
Fingers crossed the explanation is the one at the beginning of my post and it will settle.
For the pain alternate plain ibuprofen (not mixed with anything else - check label) and plain paracetamol, 2 hourly (ie take ibuprofen every four hour and paracetamol every 4 hours spacing them out by 2 hours). This helps to maintain a more constant level of pain relief.
Hope you feel better soon.