I second spironolactone.
I have PCOS, so I have diffuse hair loss that comes and goes. It is related to hormonal fluctuations. I take metphormin (which helps with insulin, which in turn keeps my hormones stable) and I take spironolactone.
I now have cosmetically acceptable hair, and lots more of it. Most people now would never know I used to cry at night and not want to leave my house because of my thin hair and acne all over my face. The medicines changed my life.
I urge you URGE YOU to go to both a dermatologist AND a reproductive endocrinologist, get hormonal tests, etc. It might be your thyroid, it might be a result of stopping the pill, it might be Polycystic Ovarian Syndrome, it might be alopecia areata, it might be only stress related. The point it, some of us have had this too, and this is what helped.
I also want to tell you that you are not alone and it can totally get better.