TMI: Has your baby’s bowel movements completely changed??

My 5 month old is formula fed and has always had dark green paste like poop. He would always poop like 1 or 2 times a day. The last couple of days his bowel movements completely changed from his normal to yellow seedy mucous poop. Also, he’s had this yellow poop after every feeding! He went from going 1-2 times a day to 5-7 a day after his bottle the last couple days. Is that normal for that to completely change in color, consistency and frequency out of the blue??? My first born never had this issue so I wanted to get some feedback. He’s been acting completely normal, no fever or illness and he’s not teething yet. His formula is also the same, which is why I’m at a loss of what could be causing this. I will be calling his pediatrician in the morning.