Welcome to HealthcareMagic forum.
Please do not worry.
In toddlers the upper body is heavier than the lower body and the child may lose balance occasionally while walking . If his doctor has examined him thoroughly and there has been no bony deformity
( of hip or legs ) then it's not worrisome .
However please do give him iron supplements
as per advised and if the problem persists do get him evaluated by a pediatrician
or pediatric orthopedist to rule out any disorder of hip bone
or leg muscle weakness
To maintain his health do give him a balanced diet rich in calcium too ( dairy products , raagi etc)
Hope you find this information helpful.
Wishing him good health.