Somethings wrong

So my boyfriend fingered me last night and afterward it really hurt down there, it was a burning pain. I stopped him from doing anything else cz i was in so much pain. We didnt know what happened.  So i tried to see what was wrong and found that its actually swollen down there which is probly why it hurt.... But i dont understand what happened. Does anyone know why im swollen and sore af down there?!? 
-worried