Crusty panties...

My period started the 14th and ended the 19th. I've been super dry ever since... like hardly any discharge. But I can get wet when my boyfriend and I have sex. Anyways, my boyfriend and I had sex this morning and I was sort of dry, but I went to pee about 30 minutes ago and I had dry, crusty stuff in my underwear... it looked like legitimate sawdust. It scared me so bad. Could I possibly have an infection? Could it be from lack of lube, or what??? Is it normal? I'd really appreciate some input. Thank you.