Do I Need To Worry About My Daughter's Red Rashes On Thigh?

my 18 month old daughter gets a rash that looks like red welts on her left thigh, it comes and goes but even when it is not red you can feel the welts just under the skin. she doesnt have the rash anywhere else on her body. she did however get four red bumps that looked similiar to hives but they feel like they are scabs not smooth like hives feel. three are on her upper body and one is on her thigh. shoudl i be worried about this?