Dear Parent,
Thank you for your consult at DoctorSpring.com, I Can understand your situation.

Hand-foot and mouth disease (HFMD) is a viral infection characterized by fever and rash. Presence of severe diarrhea, though not usually seen in HFMD, may be present in your children. Being lethargy or sleepy may either be part of the underlying disease or may indicate something much more sinister.
Severe diarrhea leads to loss of fluids (dehydration) and can also cause sleepiness/ drowsiness. The fact that your daughter has not been feeding or drinking adequately over the last 2 days increases this possibility. Start her on ORAL REHYDRATION SOLUTION (ORS) fluids immediately and rush her to the nearest healthcare facility to ensure adequate hydration. Monitor her oral intake and urine output. If she is unable to take orally, she may need nasogastric tube or intravenous fluids.
The other dreaded complication of HFMD is Encephalitis (infection of the brain). It is a rare, but serious complication that can also manifest with drowsiness. Considering both these possibilities, I strongly advise immediate hospital admission and close observation for your daughter.
Wishing her a speedy recovery, and please feel free to discuss further.
Dr Saptharishi L G
Dept. of Pediatrics
Advanced Pediatrics Center
Post-Graduate Institute of Medical Education & Research