pregnacy or not ?


I had my period 6th July till 11th July. my next period is due in five to four days. today I had a very light brown discharge with some period like discomfort I had unprotected sex on 22 which according to the app was out of my fertile window and according to some was the last day of fertility. my husband finished outside me. could any chance of me being pregnant. before this unprotected sex I took morning after pills so I am pretty sure I was safe through out my fertile window. now what could the brown discharge be.