Need help!!!

i had my last period on 4th march and ended on 11th... again i started bleeding on 20th march after having sex... and it was in dark brown... it wasnt like normal period... i only had to change once a day.. like that it continued till 25th of march... i assumed its my period... n according to my calendar i had to get my periods on 20th april... but i missed my period 8 days... and me and husband had hard sex today which led to a bit pain in my abdomen.. and at night i had a pink color discharge... so i inserted a clean finger and it had light red discharge.. plx can u tell me what it could be... shuld i consult a doc immediately??