Looking for advice from those who know more about BF than I do -

I don't make a lot of milk but I do BF him as well as formula feed, his diet is 99% formula and 1% breast milk. This last week his poop has been watery hunter Green (diarrhea) but he's acting normal, eating normal and has no fever. The only thing I added to my diet was coffee, so I don't know if that's what is messing with his stomach. I'm giving him Pedialyte to keep hydrated. Does this sound normal? I plan on not nursing him all week and see what it does, he should have an appointment next week for his 2 month check up.