Brown discharge

Does lo loestrin fe cause brown discharge? I had unprotected sex as soon as I took seven activatedpills and I took a plan b like 39 min after bc it was supposed to be my fertile window and now I’ve been getting brown discharge and a tiny amount ofblood since may 17 on and off - it’s the 23rd today.. should I be worried? Is this just from the birth control? Is it bc I missed the lo loestrin fe with plan b? Am I pregnant?