Hind Leg Injury

On 2/2 my kitty Phillip, who will be 12 in August, had a right hind leg injury.  We saw the vet, physical exam determined a sprain and also that xray most likely are not needed at this time.  He was put on Metacam and Gabapentin.  He will do really well for several days, then get hyper and over do it, and the next day or 2 he'll pay the price, well we all do.  He'll be standing somewhere and out of nowhere he'll howl, hiss and limp away.  We try really hard to encourage him to rest and sleep as much as possible, but he can get hyper.  Tomorrow, 3/21 we're taking him in for an xray to confirm nothing broken or torn or out of joint or dislocated.  We think he just keeps taking a few steps forward and then a step back.  I just ordered crating materials that will arrive Friday, until then we haven't had any crating or never had a need to crate a kitty.  It'll be big enough for a small litter box, food and water, and a bed.  I'll probably sleep next to him on the floor while he's in it.  My question is, if we are all correct that this is a sprain that is taking a long time to heal because of his level of activity, will he always be this tender?

Did you brace the leg?

no, but I've asked the vet about it, and when I drop him off tomorrow, i'll follow up with them, either bracing or a soft cast, this is all new for me, I've had kitties my whole life, 52 years but I've never run into an injury like this before