My sons lab did this, they had to put him on a low dose, short term steriod treatment because of allergies. Goo Luck.
My parents dog use to do this until he would lick his hair off!! He was a healthy Laso. It is was an allergy and was treated with medication. I would suggest taking her to the vet and have her checked for allergies.
Ginger's post covered just about everything but I have one thing to add, or rather, to ask.
As a teacup poodle, do you have her clipped in a fancy poodle cut with the pompoms around the ankles and the paws shaved? The reason I ask is because depending on who grooms your dog, if you get a classic poodle cut with the pom poms around the ankles, I have known groomers who shaved the paws with a surgical blade to take them down very close. The problem is using this type of blade on the paws (or anywhere else, for that matter) can cause razor burn, especially between the toes. It's very irritating to them and they will lick at their paws until either the irritation is gone or the hair grows out enough to not poke them and bother them. So in addition to Ginger;'s sugestions, this is one other thing you can check for if she has recently been groomed.
Ghilly
How is she walking? Is she limping?
Sometimes dogs lick because of itching, and sometimes because of pain.
Check her whole leg, carefully, all the way down to her foot, gently manipulate the joints of her legs and feet too, to see if anything you do causes her to flinch.
Then check her feet very carefully, each pad, her toe nails, and also in between her pads.
That might turn up something.There could be a small thorn or something embedded in one of her pads, or she might have hurt in between them.
Look very carefully as some tiny thorns are hard to spot, and it could have broken off. You may need to use a magnifying glass, while someone holds her still.
Also notice -are there any red marks, punctures, bites or stings, scabs or swellings on her leg ?
If you find nothing at all, then it is possible this is some form of allergy. If she keeps this up, it might be wise to take her to the vet, as whatever it is could either -get infected, or just wear her down with the constant licking, or damage her skin.