I've stumbled across this thread by accident and not had chance to read all but TA - your LO might have a dairy intolerance.
I have just had this diagnosed with my DS2, he was utterly horrendous, screamed all the time, wouldn't be put down. At 9 weeks they said reflux but the medicine made no difference. Couple of peopel suggested it could be a dairy intolerance (not the same as a dairy allergy or a lactose intolerance confusingly) and once I cut it out of my diet (I was BF) he was literally like a changed baby. He's now on special formula called Pepti. I would never really have belived it but honestly it was amazing. From newborn until 5 months he screamde pretty much all day every day, now he is a really happy little boy.
This thread will show you how utterly desperate I was and my update post explains what happened.
www.mumsnet.com/Talk?topicid=8&threadid=297027#5959571
An update - for all those lovely people who offered support, advice, etc
"Turns out that the poor titcher has a cows milk intolerance and as within 10 days of me cutting out dairy and him having his daily bottle of prescribed formula rather than 'normal' it was literally as though someone had switched babies and delivered a brand new, happy, giggly baby. So thank you (and take a bow) can'tslimwon'tslim, zzmum and U(you know who you are) - you were right.
I never would have believed it but by 5 months when things were no better I tried it as a last desperate attempt at finding a solution to the screaming and it bloody worked! (I did try it at 9 weeks but gave up after 8 days as I didn't think it was working). Anyway, went to paeditrician today - lovely lady who said, yes it is definitely that, no dairy until he's one and apparently it's really commong. I said "well I wish health visitors and GPs were more aware of it!".