What Causes Feeling Of Fullness And Cramps In The Pelvic Region?

Hi,
I have a feeling of fullness and perhaps slight occasional cramping in my pelvic region - though very mild - since having sex a week ago. I have no actual pain and my pelvic area is not sore to touch at all. It feels a little like cystitis, however it does not hurt to pee. I am concerned it could also be PID but again I am not in pain. It's just a weird sensation where I am very aware I have a pelvic area. But it is concerning me that it could be an infection. I have no strange discharge either.