Brief Answer:
Causes to dark urine,pale stool after gallbladder 
Detailed Answer:
Hi, 
The symptoms you are experiencing might be related to: 
- 
choledocholithiasis (bile duct stones)
- 
pancreatitis 
which might be happening after gallbladder removal. 
I strongly suggest to do:
- abdominal ultrasound
- urine analysis
- blood work
- biochemistry testing
to further evaluate your health condition. 
If everything is ok, then, it might be related to post-
cholecystectomy syndrome, a common condition in patients who had gallbladder removal. However, you should run the above-mentioned tests first to determine it. 
With regards to 
blood in stool, 
- if it is fresh, pink blood, then, it is related to hemorrhoids (especially if you are experiencing 
constipation too)
- if not fresh, but dark or cherish stool, then, should do a colonoscopy for further evaluation (to find out the upper GI tract bleeding source)
Hope it was of help!
Dr.Klerida