baby poop question halp! pic in post beware!

okay my LO (6 months old) went over to my mother in-laws the night before last and stayed one night. yesterday since he came home he has just been fussy wanting me to hold him and stuff. he even wouldn't sleep on his own last night which is abnormal for him. today he had a poop this morning in that was completely normal for him tealish in color.and pea it butter consistency. he took a nap and has been okay since. I laid him in his play pen so I could shower I come out and he is fussing alot! he has pooped again. I change him and his poop has this strange sweet smell like breastfed poop. then i look it is yellow and seedy like breastfed poop too!!!! he is strictly formula fed! th oke other weird thing about this poop is it kinda stringy like ewcm. I called his doctor but I'm freaking out! can anyone tell me why this would happen!?