Consult a dermatologist either online or in person.
Hair fall could be due to multiple reason like high fever, stress, nutritional deficiency, genetical baldness, hormonal imbalance etc etc.
If you are you are having hair loss since more than an year, get a proper consultation and then follow the recommended treatment for a duration for an year or so with regular followup with you Dermatologist
Next Steps
visit your nearest dermatologist
Health Tips
only shampoo or only multivitamin tablets will not help in stopping or reducing hair fall