It sounds as if Daisy may have a urinary tract infection (uti) based on your description of her behavior.
Without a urinalysis, we wouldn't know for sure but these conditions are typically treated with systemic antibiotics dispensed by your vet. Unfortunately, there are no over the counter drugs that will treat them. It is important to treat these infections since the bacteria can potentially travel to the kidneys and cause significant damage to these organs, although it typically takes time for this to happen (often weeks versus days).
Some owners have found cranberry products such as Craninidin can help reduce the symptoms associated with a urinary tract infection; however, my experience is that they're best used to prevent recurrent issues rather than to treat current ones. But, they are safe and may be something to consider since you're likely to find them at local pet or grain stores...at least here in the States that's the case.
Encouraging increased water intake is something I suggest to help flush out the bladder until a urinalysis can be done and appropriate antibiotics started.
There are other conditions, though, that could explain her symptoms such as bladder stones which can mimic a"simple" urinary tract infection and can be seen even in puppies this age...it's not common but I've seen it. Additional testing such as x-rays or ultrasound would be needed to rule this in..or out.
I'll include puppy vaginitis on the list although typically these puppies will have a creamy, sticky discharge around the vulva and will be licking the area.
I wouldn't necessarily consider this to be an ER type of situation but I would certainly encourage a vet visit tomorrow if possible.
I hope this helps. Deb