I remember reading a book 12 years ago called No More Colic. It worked. This doctor said that 99% of the time babies cry for two reasons, 1. hunger, 2 tiredness.
Following my babies natural rythyms from birth, I noticed that they didn't want to be up long. At three months, I would feed them and burp them,diaper them, and after 15- 20 minutes or so awake they were ready for a nap. Babies who do not get the right response to their cry will increase the intensity of it, and if the need is not met they can get frantic or even unconsolable. They will eventually pass out from exaustion. Some babies just can't handle walking, bouncing, swinging, it become a STIMULANT and backfires. Put the child in the crib (remember she is not crying for stimulation or company, she is crying out of tiredness/fatigue.)She will cry until she falls into slumber because that is when the need gets met. babies grow extremely fast, faster in the first 6 months of life than any other time. And babies grow- while they sleep. That is why they sleep so much.
I think food allergies when breastfeeding are a third reason for crying. (food allergies are more common now than when that book was written because of all the increased chemicals in our food).