Unease baby. Guidance will be helpful.

My baby is 1 month old, he is spliting out the milk and at times he does like something is coming back to his mouth. He also puts lots of pressure for poo n potty more over he keeps on pass watery potty with every poo apart from regural motions. His face turns very red while passing poo or potty. He also makes some wired sound while putting pressure for poo/potty and in general also when ever he feel uncomfortable. All this makes him so uncomfortable as in i have to keep on changing nappy (around 15 to 20 for watery and very small potty), which disturb his sleep as well. I do keep on burping him while feeding n afterwards as well. I do apply hing on his tummy as well but all this are not helping much. Baby is completely on breast feeding and I too is not having any spicy or heavy food. His doctor is saying is baby is fine but I see him all day and could realize the level of uncomfort he is going through. Any guidance will be helpful.