I read recently in Yahoo health that these symptoms can be associated with ovarian cancer, which was previously thought to be symptomless. Especially the frequent urination during periods was pointed out as frequent in women who suffer from this disease. check out Yahoo health or read up on ovarian cancer. Best of luck.
Your symptoms sound like a bladder infection, which is easily treated. In order to be properly diagnosed, you need to go to your doctor. You will have to give a urine sample which will tell if you have an infection or not, and he/she may put you on antibiotics. If this is the case, be aware in advance that some antibiotics may cause a yeast infection. If the pain changes, you will need to get treated for that aswell. Trust me when I say, it's easier to see a doctor than hope the pain will go away.
This sounds like the symptoms of pregnancy to me. If there is no possibility of that, then I dont know what it could be.
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I began having this problem too when I was around 18 yrs old. It gradually got worse until my gynecologist recommended I see a urinologist where, after a cystoscopy, I was diagnosed with interstitial cystitis. It is a bladder disease they are finding in young women more and more these days. It might be a possibility if you are having frequent urination and pains. I suggest you do some research on it as there are many things that trigger these symptoms that can help such as not drinking caffeine, staying away from acidic foods, etc...