After-sex discharge, this has never happened before!

ok so i'm a 17 year old girl and i guess you could say that i know my sex... i've had sex before, but this time the after math was really worrying me...well recently my current boyfriend and i have had sex... prior to sex we were both working ourselves up, (so meaning no masterbation or foreplay of any sort, so we'd be really turned on when the time came)... now during that week i was experiencing some weird think whitish mucus discharge, and i just thought it was my ovulation time of the month, so i was ok with it... and then we had sex the first time together and afterwards i didn't have any discharge at all, like i cummed and everything but for two days later no discharge of any kind. and he told me i made a mess on his boxers and when it dried it flaked and stuff, and that's never happened before so i was wondering if that was normal??... on the third day we had sex again and it was amazing, and i cummed again, but this time afterwards i've been having some whiteish discharge, like it's thick and i sometimes think it could be sperm, but i'm pretty sure a week later it shouldn't be still happening... so to sum up, what i'd like to know is is dry vaginal cum usually dry white and crusty and if not tell me what it's supposed to be... also i've never had an std or an infection, and i've never experienced this discharge before...what does this whiteish thick discharge mean?...