I'm also a federal employee, with USDA. I don't know which dept you work for - but are you eligible for Voluntary Leave Transfer/Donor Program? Its where if you have a medical emergency, you can put a request in, if you're approved other employees can donate leave to you, for as long as you need it. I have co-workers who have cancer and been on donor program for over a yr. See the link below for info. The lower link is for fact sheets on different leave options. HOpe this helps.
http://www.opm.gov/oca/leave/HTML/formindx.asp
http://www.opm.gov/oca/leave/HTML/factindx.asp
You can check with your HR staff or supervisor for info on this, if its available for your dept.
