I finished my period yesterday so then i had sex but today i have a burning red itchy vagina what could have caused this ?

A yeast infection: A yeast infection is most likely, but you need a physical exam to make sure that you only have a yeast infection and nothing else. See your family doctor or your ob/gyn.

Possible vaginal infection: The red burning and itching signifies a possible vaginal infection. The vaginal infection most likely is a yeast infection. Over-the-counter yeasts medications may be helpful. Sometimes infection may be caused by bacteria and need to be treated with antibiotics. Please see your doctor for evaluation to also rule out any possibility of a sexually-transmitted disease.