We are all sensitive down around that same area from time to time and the discomfort can happen at any time - rather you are new to sex or have been having sex for forty years.......... IMO - I would say that this problem has a lot to do with friction - the rubbing that leaves us female feeling any thing but sexual for a day or two after we have had sex.

BTW - this could also be a lubrication problem if you body is not making enough on its own..... if you think this might be the reason to your discomfort just try some good old KY Jelly the next time you have sex...... I have heard they have a new Him/Her KY Jelly that is supposed to work wonderfully together.