Hey there sulty,
I doubt your chewing pup is anything to worry about. If it were a vitamin deficiency you would see accompanying body signs, like weight or muscle loss, weakness, etc.
If your pup is 3 months old chances are he's teething! This usually happens around 3-4 months, and can take a bit. Just like human babies, pups are likely to feel uncomfortable in their mouths during teething, hence all the chewing. Have you checked his mouth and wiggled his teeth to check for loose ones? My own pup chewed through so many of his toys when his adult teeth came in, I'd say its more likely the issue here.
The chewing should decrease as his teeth come in, if it continues past let us know, or consult your vet for some advice!