About my saliva

My saliva smells like poop. My breath doesn't smell bad, but when i lick the back of my hand and wait for a few seconds for the saliva to dry out, it smells like poop. Even a few minutes after brushing my teeth. I've searched about it and the cause might be related to phlegm? I have alleric rhinitis and phlegm never goes away in my life, never. Can somebody confirm or is there something I should check in my mouth?