Hi Priya, it might due to smooth surfaces and cold. But it is better start with a calcium supplement for him. If he is feeling difficultly in walking I wouldn't recommend to allow him to climb stairs otherwise not a problem.
N thank you so much Dr Supriya for ur help. I am myself a doctor. I thought ortolani test might help as it is done in babies. I guess I will allow him to settle for a week or so
I understand your concern Priya, start with supplement and make him walk on rough surfaces atleast for an hour every day. If there is no improvement we can schedule a physical examination.