Lower, left abdominal pain. With back pain and fatigue?

Over the past couple weeks I have gone through a number of symptoms, tests and appointments, listed chronologically;

-unable to pass gas
-unable to have a bowel movement (constipation)
-Citra-Mag and fleet enema used as relief
-Constipation and bloating persists, multiple hospital, doctor and walk-in visits
-x-rays taken, proving constipation
-ultra sound taken, showing enlarged spleen, liver and thickened bowel wall
-blood tests taken, showing high LKC and Neutrophils, 1-3 points above the high end of the normal range
-Pain in lower left side following through to lower to upper back
-Prescribed antibiotics, 1) PMS-METRONIDAZOLE 500MG, 1 dose twice daily.
2) APO-CIPROFLOX 500MG, 1 dose, twice daily.
-Once on this medication, constipation seems to have been relieved.
-Still having pain in left side and back
-Small poppy seed size black dots in stool, small amount
-Soft, pale stools, with mucus
-Discomfort in left side of abdomen still (on last day of 7 day prescription)
-Pain has been greatly minimized, without any painkillers
-Having frequent, soft, foul smelling bowel movements
-Notice joint pain in legs at random times of the day, minimal Charlie horse feeling that doesn’t last more than 5 minutes to an hour at most.

I have been referred to a GI Specialist. The specialist has sent me for a CT scan which showed some swollen lymphnodes, and mild
bowel wall thickening. The pain in my side (to the left of my belly button) still remains, however it is not constant, it comes and goes. I
have not had a firm, solid bowel movement in 3 weeks. Scheduled for a colonoscopy Oct. 20 2009.
More symptoms have developed, including fatigue (very tired throughout the day) even though getting pleanty of sleep
Dehydration, having to drink 5-8 bottles of water a day.
Back pain, in correspondance with the pain in my lower left abdomen, however sometimes the pain will go up my back to my shoulders. Small amount of pain has
been noticed in my right side (to the right of belly button) and around to back in same spot as well. This pain is not severe, however noticable.
Pressure or gas buildup in stomach area, top of abdomen. Can hear gurgling sounds, belching somewhat relieves this symptom.
Diet has consisted of Water to drink, fruits and vegetables, soup, salad, chicken sandwich on whole wheat or whole grain bread, and pizza to eat. Some pasta, etc.
Feeling like I am not holding in the liquids as I tend to urinate faster than I can drink the water. Seems like the nutrients from the food i eat doesnt seem to be
absorbed by my body.
Bowel movements have been pale, watery at times, and contain a mucus.. No blood, however I have noticed at times there will be some tiny black specks, almost like
coffee grounds. (Small amount).

In the mean time the GI Specialist has prescribed me
the same antibiotics that the hospital prescribed. 1) PMS-METRONIDAZOLE 500MG, 1 dose three times daily.
2) APO-CIPROFLOX 500MG, 1 dose, twice daily.
This time he has prescribed the treatment for 14 days instead of the previous 7 day, and the Metronidazole 3 times a day instead of the previous twice a day.

If anyone has any ideas, it would be greatly appreciated.

Thank you in advance.
I forgot to mention. I am a 20 year old male. 207lbs. I have lost weight during this ordeal. I used to weigh about 220lbs. Another symptom is my face gets hot, feels very dry. No sweat coming from my head during the last week, which is odd as I usually tend to sweat the most from my head. Seems also my facial hair hasnt been growing as quickly as normal. I also get random headaches that go away with rest. my eyes also seem to be dry.

Thanks, any advice is appreciated.