Hi! I was in the exact same situation. Dd was hospitalised @ 11 weeks for similar symptoms but she also had horrific reflux sickness that on this occasion was bright green as she'd literally thrown up so much.
it was not a happy time.
But once I'd figured out what it was everything changed. Although I will be honest with you and say that it did take quite a while for everything to get out of my system and my dd is particularly sensitive.
But within 1 month I had a different baby. She was so much happier and not screaming in pain 20 hours per day.
For us it's cows milk protein and soya. It may be helpful for you to eliminate soya now too as chances are it may upset tummy if cows milk is doing so too.
It is very hard at first but it really is doable. After a while it is even easy as its just normal.
Here are the things I cannot do without:
For a milk substitute I mainly use kara coconut milk (v widely available in supermarkets same shelf as soya) it's not so good in hot drinks but good for cooking and it's also what I use for dd's porridge/cereals.
If you are a coffee drinker I can recommend alpro hazelnut milk-I love that in coffee.
For tea the best I found was hemp milk (blue carton can get from health food shops or waitrose) it has a sweetness to it but consistency is closest to cow milk in my opinion.
Vitalite margarine for everyday use and good for baking. It is available in all supermarkets and is cheap.
Own brand bourbon biscuits are dairy and soya free. As are ginger nuts, hobnobs and rich tea.
Party rings and pink wafer biscuits are dairy free but contain soya.
Full size jammy dodgers are dairy free but the mini ones are not (logic?)
Aldi angel cake is dairy free and v tasty.
Those small ready made cupcakes from supermarkets are usually milk free too.
Marshmallows are good when you want sweets. On hot choc made with cocoa powder with a fake milk is so nice. Also kara do a choc coconut milk ready made or oatly choc milk is widely available too.
Aldi mint dark choc 'crisp' things are amazing, 99p a pack too can't go wrong.
Most good quality dark chocolates are dairy free but a lot do contain soya but minimal amounts.
Be careful with crisps a lot have hidden whey powder for instance salt and vinegar ones.
Um, also if you do decide to avoid soya too most bread contains it so you have to be careful. But cheap pittas and tortilla wraps are always fine.
The good news is that an intolerance is usually grown out of! I was told dd would hopefully be fine by the age of 3. Well, she will be 1 next week and is already showing signs of being able to have little amounts both through me and directly. For instance she can eat bread now or I'll give her a teeny taste of cake sometimes.
There is an end and there is no reason you need to give up bf. we are still bf now.
If you DO decide you want to supplement with some formula at any point or want some help with introducing solids then there are products available for you to try.
We were prescribed neocate formula which we never used as I decided to just carry on bf but it is there if you need it. There is a product called neocate spoon which is a powder that mixes to a thick, yoghurt like substance that can be used as a first food if going the spoon feeding route.
Good luck with your elimination diet 