What Causes Pelvic And Lower Abdominal Pain?

I am an 19 year old female. For the past couple months, I have been experiencing all these symptoms, and they are continually worsening:

* Pelvic pain- in my lower right abdomen. This varies from lots of pressure to a deep stabbing pain, and it is tender to the touch. I am sexually active and after sex I had extreme sharp pain in my abdomen, it lasted for awhile and hurt so bad I couldn't move.

*Irregular menstrual cycle- I had two periods last month- my first very light on 09/12/10 and the next on 09/20 something, and was very heavy. I have always had a lot of abdominal pain during periods.

*Constant bloating- Throughout the day my stomach will randomly boat.

* Loss of appetite- I used to eat a lot for a girl my small size, but I eat only one meal a day now because I feel full as soon as I eat.

* Weight fluctuations- I'm very small, my weight fluctuates between 95-100 lbs, I'm 5'3.

* Irregular bowl movements- I don't use the restroom often; when I do, at times I feel a sharp pain in my abdomen and also in my anal cavity.. And I cannot hold it for long. When I'm on my period, I have similar pain.

* Extreme exhaustion - I sleep often but am never energized. I always feel tired.

* Urgency to urinate - I will all of a sudden feel the urge to urinate and can barely hold it enough to go to the bathroom. This is constant and has been happening for months.

*Mood swings – I get depressed randomly, and then will be happy for a few minutes. I have been taking things more personally and have been feeling a lot sadder lately.

*Discharge- I started my period when I was 12 and ever since, whenever I’m not on my period I have white discharge.

I cannot afford to see a doctor, I'm unsure what to do..