What is going on?!

One month ago I had pain where my urinary track is for about 4 days and I had a lot of discharge. My mom thought I had a UTI but it wasn't that. It went away for 2 days then I started cramping and my period was really late ( like always) so I thought this was a sigh that my period was coming. That night I got a cramp that didn't feel right and was really painful. The pain was progressing and then I got nauseous so I went to go lay down and when I did the pain went from a 7 to a 10 and it hurt so bad the pain lasted 10 or more and my mom asked my if I needed to go to the ER I told her I thought I was ok. I was sore for 2 days. I started my period about a week later and it was normal. I am starting to have the same pain near my urinary track. I don't know why I am having this pain but it is an annoying pain. I don't have any sexual activity and I am 15/16. I hope to be going to the doctor soon but before I do what do you all think is going on?