Hello Actually silver has disadvantages and so used very less these days instead we use tooth coloured filling called composite So please change it The pain might be because of its component mercury which expands

Hello it is difficult to pin point a specific reason with the info at hand but I will try my best to answer 1 the filling might be too close to the nerve tissue causing pain 2 there might be an infection below the tooth that may have caused pus formation and now the pus is leaking into the mouth causing an alteration in taste The above are possibilities not a pin point diagnosis