Aye, started noticing hundreds of hairs on my pillow, and if i ran my hand through my hair i would have a handful every time, with Male Pattern Baldness it comes out slowly over months/years so its not noticeable.
I noticed i was losing an abnormal amount of hair on my crown 3 weeks ago with patches developing, went to the doctor who said that i had alopecia again, however it wasn't near as bad as the first time, and it should grow back in a few months.
It can be quite a depressing thing to deal with, i'd suggest seeing your GP then a dermatologist, its important to keep in mind that it will most likely grow back in.
I'd suggest giving this a read : http://www.patient.co.uk/doctor/Alopecia.htm