I have terrible pains down there and I don't know what it is.

[STimtom_xx]

I am a thirteen year old girl and haven't started my period yet. A couple of months ago, I woke up in the morning with the most terrible pains at my vaginal opening. They happened every minute and lasted around five seconds.
We went to the doctors and they said it was probably a urinery track infection and from that day I didn't have them again for a couple of weeks (so we decided that it wasn't).
That was on the 24th of November last year. For Christmas my family had all met up at one of our houses and on Christmas Eve (24th of December) I got the pains again. My mum said to me that it could be my body preparing itself for my period but in January I didn't have them at all.
Yesterday I got the pains again (23rd Feb) but the were only on the left hand side and were also further forward.

I have no clue what it could be as I am quite small so would be suprised if it was my period!
If anyone can help that would be great! Thanks in advance.