Baby's Poop **warning, pic in the post**

My baby is 2 days shy from turning 16 weeks old. He is exclusively formula fed. We are using Similac Pro-Sensitive and has been since he was 4 weeks old. Usually he'll poop every other day-- max he'll go without pooping is 2 days.

Anyways, he pooped today and it looked like this. Couple days ago it has been his normal soft poop but this worried the heck out of me. He didn't strain or cry while pooping this, just his normal grunts.

What do you guys think? He has been getting gas drops too.