Well,don,t get panic!As per my experience,its due to vataj rukshtajaneet upadrava,according to ayurveda.As your baby has started walking recently,this gives the solidness to leg muscles.But he also faced this diarrhea+vomiting
.This affected the digestive system and rasa dhatu also.So that the muscle weakness
is produced,which is reflected in limp.In perthes,seviour pain in femoral bone+shifting pain in knees also.Sometimes femoral neck necrosis
is also seen.The treatment should be on rasa+mamsa+asthi tatva. Proper nadi chikitsa is required.