What Causes Swelling In The Labia Minora After Sex?

Hiya, I had sex early saturday morning and since then I have a very swollen labia minora on the left side , my vagina is quite itchy, for the whole of saturday it hurt to wee however that has gone now, I m very tender and I don t know whats up.. also it s only the second time I had sex but both times I ve tried we ve only got the tiniest bit in where i m so small but even that puts me in exruciating pain? Do you know why it burns so much? Thankyou