My 6-week-old baby has gas problem where Simethicone did not work. Why?

Hello doctor,

I have a 6-week-old baby. He is only breastfeeding, no formula. He had gas problems like any other baby, and the doctor prescribed us Simethicone for infants (0.02 fl oz) three times a day to help relieve it. He eats and defecates normally (at least once a day, sometimes once every two days).

Lately, he has begun crying hysterically and inconsolably. We thought of it to be colic, so we exercise his legs (bicycle kicks) and massage his stomach. But that only soothes him for a few minutes, and then he resumes crying. Today, I noticed that he was grunting. We offered him the breastmilk thinking he is hungry. But he latched on, then immediately threw his arms up, stiffened his back and let go. Then it seemed like he was grunting while trying to poop. I know babies cry. It is how they express their feelings. But when he cried, we could figure out what the reason was hunger, discomfort, wet diapers, etc. But now, we are dumbstruck. Please help.

Thank you doctor,

He does not fully regurgitate but spits up a little every now and then (looks like curdled milk white in color). There are times when he will cry during a feeding, bite and let go, even though he has not fed in a while. Often, he will fall asleep while feeding or make noises or cry while feeding. Such inconsolable crying has not happened since birth. Usually, he only cried when hungry.

Perianal area is not red. I feed him nothing except mother's milk. Simethicone 0.02 fl oz for three weeks now, and a generic sodium chloride nasal spray for nasal congestions for a month. He was also prescribed Paracetamol after his vaccinations (0.03 fl oz twice a day).

Yes, we burp during and after feeds. When he tries to pass stool, it seems like he is forcing it. This usually happens when he has not passed stool all day. And he does this especially while feeding (a lot of grunting and sometimes passing flatus). But when he actually passes stool, he looks quite relaxed. In between episodes, the baby is active. He will move his arms and legs around from a lying down position in a playful manner, make funny sounds, etc.