help me please

Ok for 2-3 days I have been having medium to heavy bleeding but today is the 3rd day and I'm not bleeding anymore my periods have always been regular 5-6 days I'm also having lower back pain cramps and tender breast I was using an app which told me my ovulation day was on the 24th but it was really on the 22nd I had sex on the 23rd thinking I would be ok if he pulled out we also had sex on the 18th and he came in me but I have googled it and it's not time for implantation bleeding yet so I don't know why I'm bleeding cause my last period was April 9-13 am I pregnant or what's going on please help