Just had a real shock

Ruby was playing, not rough just doing a bit of training and all of a sudden she got up and started yelping and limping, lifting one of her hind legs, we picked her up and rubbed her paw incase she had something in it. She then was fine and ran around etc but it was shocking to see I thought oh my god had she had a muscle spasm or something? She had her vaccine this week also.
My little girl was crying and so upset seeing our beloved Ruby in pain. Rang the vet and they said to bring her in, but Im not sure whether too as she is ok now, we looked at the floor after and found a very small crumb of a biscuit and it was very hard so think she may have stepped on it or was stuck somewhere in her paw.
goes to show how much we love her already as it has shaken me up to be honest, I will monitor her closely as I do anyway I can always take her to the vets later.

So sorry you have had this fright.You do need to see the vet as this is possibly a sign of a joint issue. Has the vet checked for a luxatting patella (knee joint)? This unfortunately is a common problem in small breeds including cavaliers. The vet should be able to tell from pulling out the leg and checking the joint whether it is luxatting. I doubt the issue would have been biscuit.

Luxatting patella often tends to show starting from about four to six months old so it is quite important to have a vet check for this. It can appear at a younger age though too. She might have sprained something as well -- either way, she should see a vet if she was favouring the leg and limping. Luxatting patella affects the hind legs. If it is her patella this will start to repeat itself.

On the other hand she must be near getting her final puppy series injections -- if so you might wait and have her checked then as if she is 10 weeks it must be in the next couple of weeks? -- but I would not just wait and monitor a dog that has been limping, myself, I'd have the vet check the legs.