Just an update on this for the information of all those who have so kindly posted advice.
Apparently the child has stopped limping and the 'specialist', by which I presume the grandparent means a pediatrician, has diagnosed a 'viral hip.'
This doesn't mean much to me other than to convey the impression that the specialist hasn't a clue. Perhaps I am wrong in so thinking.
Anyway, all now seems well and many thanks again. Quite a thread and long may it continue!