Hello, I'm Dr. Deb and will do my best to help you today.
I'm sorry for this concern for Bella.
If she hasn't had a bowel movement for 5 days, then oral laxative probably aren't going to get the job done. I might follow up with them after she starts to produce stool and I'll provide a separate list of options for you to consider below.
But, for now, the following is what I'd suggest:
1. If you have a large syringe or small turkey turkey baster, you can administer a warm water enema. Obviously, this is not for the faint hearted. I would lubricate the end of the syringe or baster, gently insert into her rectum about 1 inch and gently squeeze the warm water into her.
You may need to repeat this procedure several times to loosen up the hard stool.
Every step should be done gently so as not to hurt her.
You'll need someone helping you since she may not enjoy this procedure very much. I'd wrap her body in a towel with just her tail and rectum sticking out the other end.
2. Pediatric glycerin suppositories (http://pedia-lax.com/products/liquid-glycerin-suppositories) can be given to cats. You'll want to read the label closely and make sure that glycerin in the only ingredient; those with phosphate (such as Fleet enemas) can be toxic to cats.
You may have to force fluids/nutrition into her if she hasn't eaten in a few days. I'd mix canned food with lots of water in a blender and use a different syringe or small turkey baster to dribble this mixture into the side of her mouth.
Oral laxative options for use if/when she's starting to produce stool and is eating.
1. Hairball laxatives such as Laxatone or Laxaire which are brand names but every pet or grain store will carry these products. I usually suggest 1-2 inches 2-3 times a day.
2, Canned pumpkin (NOT the pie mix) at a dose of 1/4-1/2 tsp per day.
3. Over the counter, human Miralax at a dose of 1/8th-1/4th tsp daily which can be increased until soft stools are produced.
I hope this helps and that you're able to provide some relief for her. Deb