Missed Infant Gaviscon

Hi, I'm new to this.  

My little boy Is 4 weeks old today and was told a week ago that he is suffering with reflux,  silent reflux I think as he is hardly sick  anymore but you can see his little face in pain when the acid comes up into his mouth and his back arches violently . He was really difficult to get to sleep and irritable all the time and always looked in pain bless him. It was making my baby blues even bluer . 

So.. . . .  Doc gave us infant gaviscon to use and iv been using it at evening and night feeds mostly as you can only use it 6 times a day, that way I thought he would have a better chance of sleep.  

So all finally seemed settled down and he seemed very content. Well, one night ago his nanny and grandad had him overnight as they wanted to give us a decent nights sleep as he's also quite figgity in his sleep and keeps me awake and they have looked after neices and nephews that young so I knew he'd he fine with them. Only thing is yesterday morning when we picked him up nanny tells us she FORGOT to give him any Gaviscon the whole time they had him!!!!!!!   She said I shouldn't worry as he has been fine without. Well now, and lastnight he's suffering again!!!!!  So I'm guessing it was the gaviscon that was doing the trick. I'm so annoyed but I guess it was an honest mistake!! 

Hes on 4oz about every 4hours and he's had it in every feed ( 4 feeds) since she revealed he'd missed it. I'm just wondering if anyone else has had the same experience and how long it seems to take to get back into his system!?!?!? My poor little baby is suffering!!!  Help!!  Xx