we just got a young guinea pig who seems to have the symptoms of vitamin C deficiency. Not active, seems to hop around, hind legs seem sore, squeaks when brushed or rubbed upwards instead of down. will his joints, and skin get better when his vit. C is back on track? also should I give him as much as possible to try to catch up or just go from here with a normal cavi diet?
Hopefully he can be nursed back to health
We love you Howie Dewitt!! You're the cutest little squeaker ever!!
Get Well Soon!!
Yes, if you give him the right medications then it is possible for him to get back to health. Give him lots and lots of oranges (no peel) and play with him. Hope I helped! 
I recommend you take Howie to the small animal and exotics vet. a vet could better diagnose the problem.
Don't assume that every guinea pig malady is scurvy.
If you can't afford or find a vet that knows guinea pigs, I would thoroughly read this website:
guinealynx.info/index.html
If is it indeed scurvy, I would get a syringe (no needle of course) and feed him liquid vitamin C (ascorbic acid) like you would with a baby bottle.
Quoted from guinea lynx:
If my guinea pig has scurvy, how long will it take to get better?
Recovery from deficiency usually requires a week of treatment.
Give 50mg/kg once a day or
Give 25mg/kg twice a day
He could even have symptoms for something else… as it does sound exactly like one of my old boars had and died from last year at only 5 months of age, and we don't really know what was wrong with him, although have suspected it to have been mange mites. Sam had very bad skin, fur loss, wasn't able to be held properly because he'd literally scream as though he was in agony whenever you'd touch him, and couldn't walk/run well on his back legs, and yes seemed to hop too. In this case please take him to a reputable guinea-pig vet to have his skin tested and possibly an injection to get some vitamins etc inside him.
I hope its not what my Sam had because he ended up dying after an evening of seizures in my arms and I wouldn't wish that upon anyone to have to go through.