When you say he struggles - do you think he's constipated at all? Or just uncomfortable when he goes?
Plenty of wet & dirty nappies?
DS was like this and it improved greatly by the time he was 12 weeks or so, and you may find this is something that improves with time.

I don't know anything about the product you mention, but my understanding is that the best source of probiotics your baby can get are in your breastmilk.

One thing that we found helped ease tummy pain was Brauers stomach calm.

All the best~~