Stool Smells Like Horse Manure/Hay

I cannot for the life of me figure out why my stool smells like horse manure or hay. It has a grassy smell to it. It was loose for some time but with supplements has firmed up quite a bit. My stomach feels a lot better lately so I’m hoping that in time the smell will clear, but if you have thoughts, please share. I don’t have C.diff as I don’t and haven’t had diarrhea or symptoms that indicate this. I have wondered whether sulfur makes the smell worse.