I am very sorry that Bella is seeming to have more and more trouble passing urine, was urinating blood, and now seems unable to pass urine at all.
There can be many reasons to have difficulty passing urine and blood in the urine.
We often think of an infection but also crystals or stones in the urinary tract, masses in the urinary or reproductive tract are possible causes as is a clotting disorder.
She needs to see a veterinarian, ideally as soon as possible as she sounds uncomfortable, but also because she seems to be unable to pass any urine. When a complete obstruction occurs urine builds up in the bladder, places back pressure on the kidneys which affects their ability to function, waste products build up in the blood, and electrolyte levels become unbalanced causing the pup to strain repeatedly, and eventually vomit and become quite lethargic.
If she is blocked (truly unable to urinate) this is a true medical emergency, she can die from the toxins and changes in electrolytes in her blood which can lead to fatal heart arrhythmias.
She needs immediate veterinary care.
As long as she can pass some urine this is not a rush in emergency, but once they truly cannot urinate at all an emergency visit is best.
It is very uncommon for females to develop a true obstruction, as their urethra is relatively wide given their body size. But with her history of a previous episode of bleeding that only partially cleared with Clavamox makes me concerned she either has radiolucent calculi (urinary tract stones that can't be see on normal radiographs, only with contract material or on ultrasound) or a mass i her bladder (usually a transitional cell carcinoma) that is blocking her outflow tract.
If she can pass some urine all you can do for her at home is encourage fluid intake to flush out her urinary tract. Add water or low salt beef or chicken broth to her food or feed her canned food to encourage eating and increase her fluid intake.
Give her ice cubes. Offer her fresh water frequently.
And make sure she gets out frequently to urinate.
If she is straining but is truly unable to pass any urine, is vomiting, runs a fever (more than 103F rectally), has a tense, painful abdomen with gentle pressure, or her gums become very pale it is time for emergency veterinary care.
Let me know if you have any further questions