I know how it feels... I just got back from three weeks in the hospital with my husband. Like you, he got out and less than 24 hours later, was back in with the complications he had. It's rough. There's stress, worry, disappointment, fear...and it's even harder with a child because you can't let them know that anything's bothering you.
If you are religious, please take the time to visit the hospital chapel. There will be someone to cry with -- get the stress out if you need it! just do it if you feel you have to! -- and pray with you and for you.
I feel for you! Your family is in my prayers.