Aiyo, formula constipation ni memang stress kan! Few of my mum friends also kena the same thing, tengok macam formula dia tak suit je, perut baby leceh. Since your doctor dah check dan suggest balik Similac TC, maybe buat switch lebih slowly next time (gradual mixing untuk 1-2 minggu) sebab sudden formula change boleh trigger the bloating & green poop, that's usually sign perut tengah adjust atau ada lactose issue. Kalau sudah try 3 brands & still kembung, sebaiknya balik jumpa doctor & cerita pasal green stools & gas tu, mungkin ada sensitive perut or milk allergy yang perlu special formula (hypoallergenic type like Similac Alimentum atau Nan HA). Jangan tengok-tengok je, doc boleh guide mana formula yang betul untuk baby you. Stay strong mama, ni phase je!