What is this!?

on thursday night my fiance and i had and during, it felt like he was hitting something and it was uncomfortable! not unbearable. Well yesterday morning i woke up with a dull achy pain in my lower left pelvic and abdominal area, last night the pain got a little worse and my lower back and thigh started hurting. I took some pain reliever and put heat on it, and it helped, i was not disturbed during sleep either by pain, the pain has continued on through today, and its sometimes sharp and the majority of the time is just a dull ache like a headache that wont go away! I have no fever or bleeding or excruciating pain. I have never been diagnosed with cysts or anything like that! what could this be when should i worry!