I have an antifreeze smell in my second floor bathroom (nothing in the next door bathroom or the first floor bathroom)

What fixture is the smell the strongest?

The toilet

First check the bowl level. Is it low? Sniff around the bowl and the base. If the smells'sstronger at the base replace the wax seal. If it smells worse in the bowl check the little tube that runs from the ballcock to the white overflow tube to see if it's conneced and water's coming out. This is what fills the bowl. Just had that happen in my master bath. Had a bad smell and was about th pull the toilet when I noticed the bowl level was low. The little tube was off the ballcock. Hooked it back and the smell is gone. Good luck, tom

I'll try that. Thanks