Suggest Treatment For Chickenpox

My 20 month old daughter has a severe case of chicken pox. she hasn't had her 18mth immunisation. She woke with the spots on Sunday and it has been confirmed by our local doctor. Yesterday she had very bad nappies with a mucas and a pale loose consistancy and this has continued this morning. She had lost her appitite but ate last night some rice. I can't get into my normal doctor today. Should I be concerned?