Haih, I totally understand your worry! Dari description you, the greenish poop 2 days ago sounds like normal transitional poop, doesn't sound like foremilk issue la, especially at 4.5 months. But honestly the putih2 like worms texture you're seeing today is a bit unusual, could be just how the poop mixed with spit-up or milk curds (which is normal BF baby poop), tapi better you snap a pic and check with your paediatrician to be safe, just untuk peace of mind you lah. A few of my mum friends had minor freakouts like this too and turned out fine, but doctor can give you the proper answer faster than guessing online. How's your baby's mood and feeding otherwise?