5 weeks - slight blood tinged discharge

I work in a residential unit for teens with behvioral issues and yesterday I got hit in the head and ribs by one of them. I went immediately to the ER and they treated me. I let them know I was 5 weeks pregnant. They said the baby is well insulated at this stage and should be fine as I was not hit directly in the stomach/pelvic area. Today I noticed a very slight brown tinge to my disharge when I wiped so I am freaking out now. Could this be related to the assault or is it normal at this stage? Going to call my doctor tomorrow. Ahhh!!! :(  Send my baby love!