Comfort milk at 11 weeks

[KgZm]

Hi all, DC 2 has terrible collic ans after a second trip to GP as he basically refused his milk, screamed the house down unless I held him upright and was really uncomfortable when passing wind or pooing. He also struggles to bring up wind and has over the weeks started to take less and less milk at each feed. So I switched him to Cow & Gate comfort from Aptamil 1. My questions are as follows:
is 11 weeks to late to change milk, if not how long until I see a difference? So far the only thing Iv noticed is that he iz no longer screaming during feeds?
as the milk is thicker, will he take less compared to normal formula and will this impact his weight gain?
while he is wetting nappies, they are not as wet compared to when he was on normal formula. But his number 2 nappies are heavier and he is pooing once a day or 1.5 days, where as he was only pooing every second or 3rd day on regular formula.
We are on day 4 so far.
Thanks

Have you thought it could be cmpa and reflux ?

If you haven't had any advice from anyone medically qualified eg Dr. Midwife, Health Visitor, then I think that you really should. If you have been advised to do what you are doing, and only want advice because it is the early hours of Sunday morning, then of course it is fine to ask Mumsnetters for help.

I hope you get some useful advice from someone @KgZm, unfortunately I am far too old to know anything about the different formulas, so my only advice can only be to contact one of the professionals in this area first thing on Monday morning. Of course if anything becomes an emergency then you should take dear baby straight to A & E, or call an ambulance. Good luck OP, most things work out just fine with a little bit of diligence, but with an 11 week old I don't think you can be too careful xxx

Hi both,
Reflux maybe, but not sure it is CMPA?
Yee the doctor advised me to try the comfort milk, so just looking for experiences really.
Thanks :)