Re: 17 y.o. DD has mono!
I've personally never had mono, but I had a friend in high school who had it. She was out of school for a month and when she did start going back, she could only go part-time. She was just so tired and worn-out that she couldn't handle a full day of school. She did get over it eventually but it was hard on her academics to be away for so long. So from that, I would agree w/ the others that your DD needs to REST and REST and REST.
Lydia, Mom to - Monster #1 (6/06 - ASD) & Monster #2 (11/07 - ASD)