My baby 10 months is just getting over fifths disease and has been sleeping literally almost all day and still very sweaty when sleeping?

Probably OK. Fifth (not "fifth's") disease is caused by a virus, and young children can be slow to recover from viral illnesses. Also, the medications used to treat such illnesses can cause drowsiness. But if the drowsiness persists, you'll need to check with your pediatrician.
Viral infection. Flu like symptoms with rash on face to extremities looks like slapped face apearance last 1to2 weeks. Treatment is symptomatic.