I'm sorry that her diarrhea has come back.
I know you've told me that you've been feeding the Solid Gold for a long time. There are some who believe that dogs will develop allergies to foods that they've been fed for a long time. If the runs go away when she's off the food, and come back once you put her back on it - I'd have to be suspicious of the food.
Having white blood cells in her urine could indicate an infection, and most likely a bladder or urinary tract infection. The stones normally form after a prolonged decrease in flow going throught the bladder. Is she peeing the same amount as normal or is it less or more? Sometimes white blood cells will show up even with no infection - the white blood cells are the body's army and are sent out to do battle with whatever the body thinks has invaded it. Sometimes inflammation can cause the body to react, or some kind of irritation. And sometimes the immune system just goes haywire.
It could still be the giardia - everything I've read says that it can take more than one round of antibiotics to get rid of those buggers.
I know that the pumpkin seemed to help her last time, have you tried that again? Personally, I think the vet food helps because of the additives they put in - it's definitely not the sub-par ingredients. I would imagine they are trying to sell you the I/D food, which is for digestive issues. Here are the ingredients:
Ground Whole Grain Corn, Brewers Rice, Dried Egg Product, Chicken By-Product Meal, Corn Gluten Meal, Pork Fat (preserved with mixed tocopherols and citric acid), Powdered Cellulose, Dicalcium Phosphate, Chicken Liver Flavor, Iodized Salt, Potassium Citrate, Choline Chloride, Calcium Carbonate, Potassium Chloride, Dried Beet Pulp, Soybean Oil, vitamins (Vitamin E Supplement, Niacin, Thiamine Mononitrate, Vitamin A Supplement, Calcium Pantothenate, Biotin, Vitamin B12 Supplement, Pyridoxine Hydrochloride, Riboflavin, Vitamin D3 Supplement, Folic Acid), Taurine, minerals (Ferrous Sulfate, Zinc Oxide, Copper Sulfate, Manganous Oxide, Calcium Iodate, Sodium Selenite), preserved with Mixed Tocopherols & Citric Acid, Rosemary Extract.
According to their website, the benefits of this food are increased B vitamins and potassium, higher fat to replace lost energy and higher fiber. Vitamin B6 & B12 are needed for proper digestion, and can be found in any meat or poultry source (which this food has almost none). Bananas are high in potassium and also in B6 and B12. I can see that the food is definitely high in fiber - it's pretty much all fiber IMO.
I hope she feels better soon. There is nothing worse than not being able to find the source of the problem.
Livin in a Newfie Drool Zone