When your vagina itches and stinks really bad it's most commonly caused by a condition called bacterial vaginosis (BV)
The bacterial vaginosis (BV) can cause your vagina to itch and stink really bad and it's what I had one day when I had a really itchy vagina and a really smelly and stinky vagina as well.
So get checked out by a doctor.
Other causes of an itchy vagina is a rash, insect bites, dry skin or your pee may be a bit salty or alkaline causing your vagina to itch.
The reason you need to smell your vagina everyday is to alert you to any change in the odor which could be a sign of a UTI "Urinary Tract Infection" or other health issues with your Vagina.
You should know what your vagina smells like when normal so when you do take a whiff of your vagina and it smells different then it could be a sign of something wrong.
Then if you do notice a change in smell of your vagina it would be good to talk to your doctor about it.
It's normal though for vaginas to have an odor to them and sometimes the odor may change from day to day which is also normal.
But if you notice a really foul smelling odor or a fishy smell from your vagina then it may be a sign of a Urinary Tract Infection.
A urinary tract infection usually clears up on it's own but you should see a doctor just to be safe.