Really bad squint!!!

I gave birth to my son 8 weeks ago and apprx a week after his arrival my 2 and 1/2yr old daughters eye started to turn in, this has never happened before and it was quite rare to begin with it just seemed to be when she was concentrating or tired but now it seems to be like that quite alot, when shes trying to focus etc and now the other one has started doing the same too. Shes quite happy with the baby and enjoys him, i make sure i give her as much of my time as possible but i know my being in hospital for a couple of days was very distressing for her as she had never been without me for more than a few hours in her life, she still tells me now she misses me and doesnt like me even being in a different room despite my reassurances. i feel absolutely awful, the stress of the past few months must be to blame for the appearence of this really pronounced squint, Im taking her to the doctor next week and am expecting a referral to the eye hospital but has anyone else experienced this? What will they do? Is there a problem with her sight? What if shes struggling to see properly? I feel so sad for her!