Hi M.,
Don't fret, it will come back. I had the exact same thing happen to me and in fact my Christmas pictures you could see it and I had to have my husband digitally (good job) fix it in several places! Girl, and I have thick, thick hair and tons of it and use to shed all over the place, so you can imagine my surprise to see this happening to me. I thought I was gonna die from the condition!
One thing, be sure and take your vitamins and just remember that it will come back. Mine did, but it did take some time for it all to come back!!
Good Luck. Give it about 2 to 3 months and it should be ok.
G. B.