Another quick update:
Lily woke up with a normal temperature today! This is the first time her temp has been normal (98.6 or below) since this all started last Monday. And we didn't need to give her any medication during the night. I'm really hoping her fever doesn't return this afternoon.
My awesome doctor's office called again and my Pediatrician consulted with the Immunologist and the Immunologist feels that Lily has Periodic Fever Syndrome, which my doctor has mentioned before also. My nephew was also diagnosed with this syndrome, although the removal of his tonsils (which coincided with his 3rd birthday) significantly decreased his fevers.
I'm still going to keep an eye on Lily's joints and will ask the Immunologist about it as well. We will get to see him late next week now, instead of August.
Most of all, I was thrilled that she didn't have an elevated temperature this morning. I feel like my other girls have been neglected a bit through all of this and I'm hoping for a couple of fun days with them all when I'm off the next two days. We're gonna hit the beach!