Hopefully, you're already at the pediatrician's office or on your way.
At 6 months, she should be OK to have motrin (I'd confirm with the pediatrician). Otherwise, Tylenol should help with the fever. Whatever it is, the poor thing has to be feeling awful with a fever like that.
My kids always do well with a luke warm bath to try to break the fever, and then hold them and comfort them as much as possible.
Hoping all is well at the appointment today.
Don't be shy about calling the pediatrician during off hours. They're "On call" for a reason, and a temp of 102.8 is definitely a reason to call. High fevers can spike febrile (fever-related) seizures which are much more serious.