Should i go to the doc?

My two (almost three) year old suddenly has urine that smells like maple syrup and has completely regressed in terms of potty training.

His brother, when an infant, had constant maple syrup smelling urine, and a host of other things, like developmental delays and delayed speech. Strangely enough the delays cleared up when we put him on the GF diet, adn the maple syrup urine seems to have resolved.

Both boys have celiac disease.