What Causes Irregular Periods With Loss Of Hair?

I have been loosing hair daily for awhile now and I have irregular periods. I visited my doctor and he thinks stress..so recomended a bioten pill and gave me a mild nerve pill. this is still going on and my hair is visably thinning so much..what do you think could be the problem its not thyroid checked that no former medical issues and not on medication that would have caused this..