My ds2 had silent reflux and was on ranitidine from a few months old (iirc) till abound a year old.
Ds3 was born just under 4 weeks ago. He was so placid and settled and fed well for the first few weeks. Gained his birth weight back at 2 week weigh in plus an extra 1lb 2oz.
Over the past week he has become Increasingly fussy and is showing some of the symptoms ds2 did. This has coincided with me starting to have a bit of an oversupply/fast let down problem. I looked on kellymom and advice was to feed one breast per feed and try keep him higher than my breast when feeding so gravity will slow the flow. I'm also having to burp him during feeds as he swallows air when he gulps. He was pulling off and screaming when let down happened but this has improved since I have been following this advice.
Anyway, the fussing that I think could be silent reflux starts just after a feed usually. He will be sleepy from the hormones in the milk for a minute or two then his face crumples and he starts to cry. He jerks his legs and hands and if I try to sit him up to burp him he arches his back/goes stiff like a board. He seems to gulp and swallow and chew like something is coming up his throat. He get hiccups a lot. Most of the time since this started the only thing that stops him crying is if we hold him with one hand under his bum and one behind his head and kind of suspend him in mid air in a semi reclined position. In this position he goes quiet and sometimes falls asleep. If I try to move him even just to cuddle him in more of a cradle hold he cries again. If I wait a long time, about half an hour then I can sometimes transfer him on to my lap as he's in a deeper sleep then. Once he's asleep properly he seems ok. He sleeps for a while then wakes wanting a feed and the whole thing seems to start again. There are a few periods where he's awake and not crying. He likes to lay on his changing mat which is unusual if he has reflux? Although sometimes if he is laying there quite happy he will suddenly start crying as if pained by something.
Is it possible for reflux to start after a few weeks like this? It's like someone has swapped him for a different baby to the one I had two weeks ago. I was coping well and getting things done, making lunch for eg. Now I can hardly put him down and can only get things done if and when he sleeps. I feel like I'm neglecting the other two too as I'm holding ds3 a lot of the time 
Not sure what to do. I'm a bit reluctant to get gaviscon from the dr as I seem to remember you have to make it up before every feed and it can cause constipation. This seems like such a faff when I'm breastfeeding. Ideally, if he does have it I'd like the dr to prescribe ranitidine straight away without me having to try gaviscon first but I don't think they'll do this 
Another thing to mention, don't know if it's relevant at all. His poo is normal colour (yellow and seedy) and he goes frequently. Only thing is, when it comes out it's very foamy, kind of like hair mousse! Is this ok? I've asked other mums and they say their baby does foamy poo's too but I can't remember the other two being so foamy!
Any advice or info welcome!!