I have a nearly 6 year old boy, who is struggling with running and climbing. He is over weight at 37k (121cm) he has lost a kilo recently as we've started doing activities 4 nights a week. We have been camping this weekend with his friends and he is complaining he now is complaining that he can't walk 😕 I have 2 friends who have said I need to approach the doctor. He has never been very agile with climbing etc. even when his was younger (and not overweight) Anyone have any idea what this could be with his symptoms?