my daughter is 5 year old. she has a normal diet but still she is not gaining any weight.she is only 13 kg. also she has a problem of knee pain always..once when she was 2.5 year old that time she got the problem of knee infection nd she did not able to stand even.then we get her treatment and then she got fine but from then she has knee pain always..pls suggest something for her weight nd knee pain.