Rice Cereal

So for 2 days now, I've been giving baby rice cereal at around 9am. I give it to him after he's had a bit of milk to drink. I don't think he has any allergic reactions to it, but he has trouble pooping. He cries the whole time he's pooping. The poop is not that hard, it's just probably more solid than he's used to (he pooped the 2 days he had cereal). Today, I gave him a bit of diluted prune juice just to help things along. Right after he had the juice, he pooped! BUT he still cried. I'm gonna check with his pedia if this is normal. It doesn't look like the poops are super hard but the fact that he's crying so much is worrying me.

It shouldn't be funny but it actually looks like he's giving birth. I'm at the foot end trying to raise his legs and cleaning the poop as a long portion comes out (sorry if TMI) and daddy is at the other end comforting him. And you can really see if he's pushing from his face, cry, and the view from my end. I hope everything gets better for him.