Conditions that cause extreme fever
etc. produce a state of hair undernutrition
and falling out during the period of recovery (convalescence). The hair usually grows back within a few months, and the doctor hasn't erred by not prescribing any medication. If at all, you should eat a lot of fruit, dry fruit, legumes and fresh raw veggies to replenish the lost nutrients. A massage
with almond oil may also be beneficial in such cases. However, I strongly urge you not to wash your hair with harsh shampoos or soaps and to dry them with a patting movement with a soft towel so that the hair is not pulled out by the roots.