Okay so on saturday me my boyfriend had now my is dry&itchy HELP!!?

So me and my boyfriend have been dating for a few months and we were both virgins and then we started having we have had about 9 times(always using a lubricant) and then on saturday we had in a different position and now my is extremely dry and itchy its not really red and it doesn't burn and its not swollen.We had again today and it hurt putting it in until we used a lubricant we both have only had with each other so we do not have any std's why is my suddenly itchy and dry could it be the new position or that the sex was rough or am i totally off someone please give me your opinion