Holly,just a thought.When we came back from Agia Napa,last October,one of our cats,George,was limping,and basically "holding" his left paw.A neighbour who was looking after the two cats at the time,whilst we were on holiday,said that George was fine the night before,but now he was limping.
We took him to the vets,the next morning,and she said that George had an abcess,I think that's how you spell it,as I'm in a hurry this morning
The vet,burst the abcess in George's paw,gave him an injection in his neck,and gave us tablets (three),to place with his food,for the next three days.Within a day of having his abcess burst,and medication,he was fine.
I'm not saying this is the cause of your cats limp,but it is a suggestion.