I had surgery to remove a dental cyst now when i bend forward i get shooting pains through right side of my face, runny nose metal taste in my mouth?

How long ago ?: Your post did not say. Sometimes these wounds take time to heal. Your best bet is to call the surgeon who performed the procedure for a follow up appointment.

opening to sinus: If the cyst was in the vicinity of the sinus the removal may have created an opening from the mouth to the sinus. These often heal and close on their own. Antibiotics would be prescribed along with precautions regarding creating pressure between the mouth and sinus such as drinking through a straw. If it doesn't close on its own surgery would be required. Follow-up with your dentist.