What Causes Brown Vaginal Discharge Post Unprotected Sex?

Hello I had unprotected sex with my boyfriend on the 21st of this month I felt sick this morning and I have Brown discharge, it didn t last long he said he had to cum and he pulled out and nothing came out a few hours before that he came all over his stomach then fingered me So I feel like there s a chance anyways cum could have gotten inside me! Am I pregnant???