Biting paws

I know this has been mentioned before but I am hoping there might be new advice on dealing with our Lucy biting her paws. She is 2 years old today and has been biting/ licking her paws for 2 weeks. I hold her paw and say NO! to try and stop her; but she only trys to knock my hand away to start nibbling away.
Is this a yeast infection?
She licks and chews frantically then eventually calms down and goes to sleep

Another thing I ought to mention is... I believe she gives out a scent when she should have been on heat as every few months our Franky is very keen on smelling her back end and even try's to mount her. (she was neutered when still a puppy)

I would just like to mention that both dogs get on well and always want to be near each other. They are never left a lone and have the run of the garden to play with their toys.

I have a 9 month old bull staff
Hes such a good dog but from as far back as I can remember he has been itchy and scratching and a constant licker. I could never understand why.
He now has marks between all his legs and even around his penis. Some on his legs and constantly licks one paw.

I've tried to add photos but he doesn't like to sit still for very long
Can anyone help me out vets for pets Boucher road told me its allergies but straight after anti biotics the marks came back. I don't want him being on antibiotics all his life.

Bo has sensitive feet. A couple of weeks they flared up so bad he couldn't walk at all on hard surfaces. I bathed them twice a day in Epsom salts for three days, then in Hibiscrub for a couple of days, and I also put a bit of Johnson's antibiotic powder on the worst bits. In four days he was jumping around again, and even ran like mad in the house for the first time since he was a puppy. I now clean his feet with wet wipes every day and soak them in Epsom salts or use Hibiscrub if he's been somewhere very dirty like the beach.

Edit: It's also the time of year for harvest mites, which can cause nasty sores on the feet (and they itch for a week if you get bitten too!). I use Effipro for this.

It could be an infection or something stuck in the paw. Try wiping her paws off when she has been outside and if that doesn't help try going to the vet.

First call is the vets to ensure there is nothing on the paws etc. my Flo is the same but only with her rear paws. We've tried just about every remedy suggested but found that Thornit powder worked really well on one of her paws and we reapply it regularly.

Something else to try us Apple Cider Vinegar diluted and then wash the paws. In any case, regular washing of the paws should stop and sores starting. Hope there's something in the suggestions to help

remember and thoroughly dry the paws as well

Thank you everyone
I've checked for redness on her paw and between her toes "all looked fine" Even though she doesn't like her paws being wet I bathed her in salted water and wiped well.

Before I moved her mouth away from her paw last night; I took a keen interest in what she was actually doing... first she was licking her paw none-stop then she laid down to really have a good tug at her nails. I'm going out to buy some antlers today to see if this is just Lucy being bored. In one way I hope it is; but on the-other-hand I don't want it to be a failing on my part  
She goes out regularly with Franky and we also play with our dogs in the garden so if it is boredom I'm hoping new toys might solve it?

Lucy is at the vets in 2 weeks time to have her booster injections so
I will deffinitely ask them to take a look at her paws, but if she is still persistant I will act sooner.  
THANK YOU again  

                                           ((A problem shared is a problem halved))