Almost all parents of a newborn have questions and concerns, especially when the newborn doesn't feel well.

And then there's the big question: Should you take your newborn to the doctor?

If your baby is sick, here's a little help knowing what to watch for, when to call your doctor, and why.

Fever.

A fever can be the first sign of something serious.

And it can happen fast. [baby crying] Okay, but what's a fever for a baby?

You can't really tell just by touch.

A rectal temperature of 100.4 degrees Fahrenheit or 38 degrees Celsius or higher is a fever.

And it's time to go to the doctor, especially if your baby is a newborn.

Vomiting.

Now, as you may already know, newborns spit up.

But vomiting is different.

It comes out with force.

What about diarrhea?

You'll know diarrhea in your baby's diaper because it's different than what you usually find.

It's watery. [dripping sounds] And it may be a different color.

If the vomit looks a little green or bright yellow, call or go to the doctor.

And call if either vomiting or diarrhea happens for more than a day.

That's because your baby can easily lose too much water and become dehydrated.

A rash.

It's common for a newborn to have a rash or other skin problem. [baby crying] But if the rash comes with a fever or fussiness, or if your baby is already sick, call your doctor.

What if your newborn isn't eating?

Refusing more than 2 feedings may be serious.

It's a good reason to call your doctor.

Okay.

Now just in case, here are a few serious symptoms that are definitely serious.

And by serious, I mean get-emergency-help-right-away type of serious.

Get emergency help if your newborn has severe trouble breathing.

You'll know, because your baby's nostrils will flare.

And the belly moves in and out with every breath.

Also get emergency help if your newborn is limp or floppy like a rag doll, or doesn't respond to being held, touched, or talked to.

So let's go over that again: Get emergency help if your baby has severe trouble breathing, is limp or floppy, or doesn't respond.

Having a newborn who might be sick can be scary.

But understanding what to watch for and when to call your doctor can help you better prepare to get the care your baby needs when he or she needs it.

You know your newborn best, so if you have any questions or concerns, call your doctor or nurse care line.