I have a 3 month old that wants tobe held a lot. Sometimes when she isn't held she cries. I can't hold her all the time and so she sometimes cries for over an hour. What should I do.

I say hold her, shes still too young to manipulate you, I would swaddle her, she may need to feel the tight closeness to feel secure, and you may want to get one of the holding sacks and walk around with her on your back or front.