Here is My take on it.
Your son is normal, and this does happen to newborns/babies a lot, because of an immature system...they are still developing outside the womb.
Now, Just because he is "grunting" and farting a lot... does not necessarily mean "he" is in pain... babies OFTEN grunt when pooping and farting, and their face turns red. It's common. But it does not "mean" they are in pain.
IF HE WERE in pain, he'd be crying and screaming, inconsolably all day, and not sleeping at night. Which, he is not doing. He seems fine, besides the sound effects he has when farting/pooping. My son, was a LOUD grunter and very expressive whenever he farted/pooped. My daughter was not.
Now, the Mylicon drops probably does not help because he does not have a gas "problem" per say. HE IS PASSING GAS. A "gas problem" is one in which the gas is NOT passing...thus
pain. I know this because my daughter had BAD gas problems as a baby.... she did not fart at ALL, or very rarely. SHE was in pain and cried and screamed and her face bore much pain as well.... she was miserable and could not sleep... but she did NOT have colic, which was confirmed by the Doctor.... hers was just a very bad gas problem. BUT for her, we did use the "Hyland's Colic Tablets" and it did help a lot.
Now, be glad that your son IS farting and has pooping. And yes, newborns and babies DO have explosive blow-out poops! It's not unusual. You should not try and make him fart "less"... his system is merely getting rid of excess gas. That is good. My daughter on the other hand, did NOT fart and all the gas accumulated inside her... and cause much pain. Which would you want for your newborn? An efficient farting baby, or one who does not fart and has true pain?
I don't think your son has a problem. He just farts a lot and poops a lot. He's NOT in pain... so you may just have to get used to his farting/poop habits. Each child is different and he is not like your firstborn.
So, there is really nothing to deal with... your baby is fine. It's normal.
And yes, watch what you eat... if you are nursing.
To me, a farting baby is not a problem. But a baby who does not fart, is. Like my daughter. Even for her age now... she gets gas pains, not as much as when she was a baby....but still.
All the best,
Susan