foamy substance

i am 15 years old. i lost my virginity when i was 13. i had unpertected sex with my boyfriend 1 day under the tree when i was 14 and i thought i was about 2 have an origasm, but then some white foamy stuff came out and i dont know what it was. and now when i have sex with my boyfriend, he says he feels this lump thingy and its hard and it hurts him when he hits it.its been there before i lost my virginity too. i told him that it was my cherry, because nobody ever popped my cherry. so i thought that was it, but when i put my finger in me, i feel it. its like a round ball with a small whole in the middle. i squeezed it but i didnt feel anything. its flexable, it moves all around and i even tried to put my finger in the small whole. i didnt feel anything but i scared myself 2 thinking that something bad was going to happen. i need help.i need to know what it is.