My daughter got a sudden rash on one cheek that looks like fifths disease. do we need to see a dr for that? no other symptoms anything bothering her

Usually no: If she seems well there is little a dr can do for this.

No rush on the rash: Fifths disease is a virus and would present with mottled rash on belly. Without fever, chills or "toxic" presentation i would just keep her hydrated and monitor. Sometimes the heat from her face against a blanket can cause a mottled rash on one cheek.

May talk with doctor: Rashes are very hard to describe, so usually have to be examined to tell what they really are. The primary doctor can help decide if and when a rash needs to be looked at. If a healthy child is acting totally normal, and only has rosy cheeks, parents can usually wait a day to see what will happen. If the skin is getting blood spots, forming blisters, breaking open, etc.., an E.R. Doctor can check.