Hair comes out in hand fulls...

I hv a beauty question... when I wash or brush my hair it comes out ALOT... I don't mean a couple strands either.. This has been going on since i was about 13 yrs old, Im now 34. I even shed like a dog. My hubby finds my hair everywhere... I always hv my hair up in a piny tale, never down cuz of this reason. Iam so over it.. Does anyone know what I can do to help my hair??? (no its not my thyroid as I just got that checked a month ago) I know some of it is stress as Im dealing with alot.. Plz someone

anyone HELP!!!! Thank You

UPDATE: i just read on google it cld be, stress #1, genes, cancer (NO), thyroid. That its healthy to loose up to 100 strands of hair A DAY.. Im going to read how to help it... I know 1 thing is eating habits... which i hv changed alot... ive lost 54 pds in 4 months... From 254 to 200....