Teeth sore after a filling when brushing?

Had 2 fillings done on the molar on the right side. Tooth where the filling was done feels sore/sensitive when brushing. When I have the bristles on the underside, there's no sore but on the outside, it's uber sensitive and hurts. Been 2 days. Is this normal? will it go away? should I go back to the dentist? Thanks in advance for all useful answers.