What Causes Itching And Redness In The Vagina?

I've had this for a couple months now and it's on and off though. I haven't had sex in awhile and when I wear anytime of underwear and it rubs my vagina gets raw and red, and it itches bad. I've taken baking soda baths the past week and It seems like it's calming the itching down. I try not to wear underwear at all that has cotton and it's starting to die down. Do you have any idea what it could be?