There are several reasons dogs can urinate uncontrollably. Some dogs have a submissive urination problem. When they get excited or someone comes to pick them up they don't have good control over the sphincter muscle in their bladder to control their urination and they pee. I would definitely advise you to check out whether she has a urinary tract infection first - even though it was a neg. last time.

Maybe her kidneys aren't working properly take her to the vet just to be sure everything's ok

She has incontinence, either from an infection or weak urinary sphincter. Your vet has medications for both and can determine which problem she has.

She may have diabetes insipidus, its treatable and she needs the vet asap.

My Yorkie does this sometimes. No idea what causes it. It's like she is just leaking for a few days then it stops.