Vaginal bleeding during/ after sex

F22, UK! so i had sex and i noticed blood after, this was 4 days ago and it is still bleeding, although very very lightly it has gotten slightly heaver and darker. I also went for a wee this morning and it hurt but it hasnt hurt since. im not sure if i damaged the inside during and now it is bleeding and the blood is darker as its less fresh. still i am concerned as this has never happened to me before and its not my period as i came off that 2 weeks ago. im not experiencing cramps or other pains. is this something i should go to the drs about if so should i go urgently or should i make an appointment? (also i have lots of yellow discharge...)