First, the child will need omega fatty acids (3, 6, and 9). And in the Sunnah of the Prophet ﷺ, we have seen that sheep's tail fat corresponds to these omegas that may be needed.
Next, it is important for the child to have a healthy diet, based on fresh fruits and vegetables, or also fresh fish.
In addition, it will be necessary to check that the problem is not neurological or psychological in order to have an adequate treatment.
Finally, it would be good to perform massages on the child with oils, such as camphor oil, eucalyptus oil, or ginger oil, while also practicing ruqyah on him. To do this, the oils should be Qur'anized.
Also, it would be helpful to assist the child in getting physical exercise, as much as possible.
To strengthen his muscles, collagen combined with vitamin C will be very effective.