Please get baseline investigations done and show a Dermatologist.
Start by following a good diet - Eat adequate amount of protein. Your hair is made up mainly of proteins. Include skimmed milk, cottage cheese, lentils in diet.
Vitamin C, Zinc and Vitamin B are other important nutrients for great hair health. So include lot of fresh fruits, vegetables and whole grains in your daily diet.
Next Steps
Refer "How to Reduce Hair Loss: 25 Easy Ways!" by Dr. Jolly Shah Kapadia - https://www.practo.com/healthfeed/how-to-reduce-hair-loss-25-easy-ways-25454/post
Health Tips
"Top Causes of Hair Loss and Hair Thinning in Women" by Dr. Jolly Shah Kapadia - https://www.practo.com/healthfeed/top-causes-of-hair-loss-and-hair-thinning-in-women-15052/post