I have a sharp throbbing pain in my left pelvic area, can I get some advice?

1. It is a sharp throbbing pain in my left pelvic area

2. I did miss a menstrual period... but I am in my mid teens and read it was normal for someone my age to have that happen, so I'm not sure it's related.

3. Nothing I do changes the amount I experience it.

4. I am well hydrated (had problems with dehydration before, freaked me out and since then I've been trying my best to stay hydrated XD)

5. I've been having his pain all day (aka 8 hours) and it's been kind of an on and off throbbing sensation, like nothing really only a TINY bit of tightness then a sharp pain for a moment then it goes away for a few seconds again.

6. This has no chance of being a caused by sexual activity.

7. This is not cramps from being on a period.

Should I be worried? Is his abnormal? Is it serious? Thanks. :)

PS

If it is important, the dehydration problems I had was when I had severe pain in my right abdominal area which went from dull (like car sickness) to really painful, the doctors classified it as dehydration.