I am having heavy hair fall. Now thin.

This condition is called Telogen Effluvium. It's a reversible condition in which hair falls out after a stressful experience. The stress pushes large numbers of hair follicles into a resting phase. Within a few months, those hairs can fall out. Types of stress can include any hormonal issues like thyroid or any major illness like Covid. Once u start appropriate medications it takes approximately 3-5 months to start seeing any visible difference. U will know if the medication is working if ur hair loss reduces. Growth of hair will occur only post the cessation of hair loss. Normal hair fall upto 100 a day is normal. If it is more than 100 then it is a cause of concern that needs to b addressed. It's a reversible condition but needs to b treated to prevent further hair loss. Consult a Dermatologist.