she probably has an uti (urinary tract infection) that would cause burning on urination or a std hich would also cause the same symptoms u need to call a clinic for further testing
If your wife just got her period, I would say she is not pregnant. If she has an irritation around her vaginal area, she could have not been well lubricated during intercourse which would cause this area to be sore. Consult a doctor to see what she can apply to help ease the discomfort, or she may develop an infection if untreated.