Hair thinning is often associated with changes in hormones like pregnancy and menopause. It also occurs with low thyroid and high testosterone levels as well. Since it takes about 3 months for either increases or decreases in hair growth to be noticed, the changes now could have been started several months ago. Stress and certain medications are other causes for hair loss.
Have your doctor check your hormone levels including estrogen, thyroid and testosterone. You might also want to see a dermatologist to check for any scalp disease. The number of days you take progesterone is not a certain fix. but if you want to try changing the progesterone, you can also ask your doctor about lowering the dose and continuing it all month.
Machelle Seibel, MD