Hi R.,
My heart goes out to you, sweetie. Your story sounds so similar to mine 7 months ago. My son, almost 8 months now, wanted to suck/nurse all the time and cried all the time. He could fall asleep in my arms after nursing and as soon as I laid him in the crib he would wake up crying. He would also wake up at 4-5am screaming and pulling his legs up.
After much ado, we figured out he had both reflux and gas. He was solely breastfeeding, and so I was convinced something I was eating was giving him gas. Many people will tell you changing the mother's diet won't make a difference, but it absolutely did with my Ryan.
It took many months of trial and error, and eventually eliminating EVERYTHING possible that could bother him, then reintroducing one food at a time, to figure out what was happening. Ryan had gas and tummy pains if I ate any diary, nuts, or beans (including soy). Yes, ALL those foods. He was a different baby after I figured this out and cut them all out of my diet. I suspect this doesn't work for all babies, but I do think that MANY babies are sensitive to multiple foods their mother is eating, and so if you don't cut them ALL out, you don't notice a difference.
Every month or so I would try one of the foods Ryan was sensitive to, to see if it still bothered him. At around 7.5 months he seems to be able to tolerate me eating some nuts and beans, and I just tried dairy last night and things look good so far. Yes, it is very difficult to cut your diet back so much, and I know many women have told me they wouldn't be able to do it. But if you saw how much pain my son was in and what a completely different baby he was when I cut those foods out... it would make all the hard work worth it! Breastfeeding my son was very important to me, so I made it a priority to figure it out instead of switching to formula.
If you want me to send you the list I compiled of all the foods I cut out for 3 weeks to test out if there was a dietary connection (there were A LOT), just send me a note. I'm happy to help you figure this out so you can continue to breastfeed your baby girl and get rid of this pain in her belly! In the mean time, Baby's Bliss Gripe Water really helped us when he had terrible gas.
Hang in there, R.... you are doing a great job! These first few months can be SO HARD!
Warmly,
L.