Celiac disease can set off leg numbness, or having a spinal subluxion. Basically, if an extremity is numb there's a constriction to the main nerve feeding that extremity. The constriction can be due to swelling causing pressure. If anti-inflammatories help the condition, then that's what's happening.
A nerve test can test the strength of the conductivity of the nerves, so it might be a good idea to see the doctor just to confirm what's going on. They might not have a good cure, but a good diagnoses is better than none.
For now, best to avoid common allergans like wheat, corn, white potatoes; drinks lots of water, ginger tea, garlic, turmeric, digestive enzymes (all good for inflammation). Chamomile tea helps the nervous system, strengthening nerves.
It might be a good idea to visit a chiropractor. Could be the stress of the dental work threw out his spine. If the dentist didn't use the right kind of dental dam, he may have swallowed a bit of tooth or toxic old filling? if that's a possibility, a bit of bowel cleansing may be in order.