Talk to the Pediatrician. Baby crying could be due to many reasons or even more than one reason... teething, colic, gas, constipation, hunger, over stimulation, over tired,pain of some kind, etc. For teething.... there are over the counter oral pain relievers specifically for babies...I prefer the homeopathic types versus the 'numbing' types. My Pediatrician does not like the "numbing" gels as it can also numb the throat and affect swallowing etc. But really, if the baby is crying that much, I would ask the doctor. I know it's not easy.... good luck.
~Susan
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Another thought: you also want to make sure the baby is on par developmentally... hitting developmental marks "normally" etc. and is having proper intake levels when feeding etc. I have known at least 3 babies that were not taking in "enough" breastmilk/formula....and so the baby was basically hungry all the time. The Parents did not know this...they would just say their baby has a small appetite or wasn't hungry. Realistically, some babies don't know how to send out hunger cues (thus they cry all the time) or they don't know how to suckle or "drink" from breast or bottle properly. Thus, a lactation consultant or doctor can help. In the 3 cases I observed, the babies weren't growing well, or developing on par, didn't drink well... and was in the lower percentiles for weight etc. Once I told the Parents and the Parents started feeding the baby more, and got help for it, the crying lessened and the baby slept better too, and the baby started "growing" more, and developing more. But, this is called "failure to thrive" which may not always be the case, or your case. At each age, or month, a babies intake of breastmilk/formula increases too, when going through growth-spurts. I've just seen this too often, where baby wasn't being given enough intake, and it affects them and their development/growth. Just wanted to mention it. It may not always be the case. But just in case. :) Again, good luck and take care!