Dont know what to do!!!!

I have a set of preemie twin girls that are 7 weeks now I had them at 33 weeks and they stayed in the nica for almost 4 weeks....they are completely different twin a came home almost a week after twin b was home n she has been crying all say day in and day out and the doctors says that nothing is wrong with her all her test came back negative from everything they don't even kno why she just cry bad enough im doing this by myself there dad isn't n the picture I just wanna scream but I can't cause she will sense something is wrong smh I just wanna cry z😢😢😭😭