I am on the pill, had sex day after day after period. Day after I peed had red on toilet paper. Then day after brown spotting. Runny nose am I preg?

Low possibility. To get pregnant, you must ovulate. Ovulation occurs 14 days before your period. So depending on how often your period comes will determine if you can be pregnant. Day 1 is the first day of your full flow. If you have 28 day cycles then having sex around day 14 will put you at risk of pregnancy. Being on birth control suppresses ovulation so you are most likely not pregnant.