Extreme pain during sex.

So everytime I try to have sex with my bf, there is a horrible burning/stinging pain in the opening of my vagina. The pain has become so unbearable that I have to stop. I believe it may be an infection. Any ways to treat it over the counter?

Any advice on what this is rlly appreciated💚

Update-

Since there isn't rlly any other symptoms other than the pain I decided to lay off of sex for a week or two, drink lots of water, and perhaps start taking a probiotic. Hopefully it'll heal on its own, if not, I will schedule an appointment with my doctor.

Thank you for help and advice :)