Short Covering and BuyIn

I was short this share and today I had to cover because of my broker. Here is the note that I got today:

Your account is short XXX shares of AMAG. We are no longer able to borrow all of the shares. You may need to buy back XXX shares to cover the short before 1:30 p.m. CST on 6/1/2007, or the security may be bought in for your account.

I covered a short while after that. And looking at the charts, I feel this is going down. I spoke to the account rep and he says that they don't have this stock in their inventory . Here is what I can make out from this:

A. This one is going down and they screwed me
B. Downside is limited as everybody has already sold.

Time will tell.