Question for moms of 2 or anyone with advice!

Ben is home, thank goodness, and is the easiest baby ever... and a terrific nurser (no shield!) to boot (knock on wood).  So that has been great.  Sam, however, is having a tough, really tough, time adjusting.  He has not napped, has cried so hard that he has thrown up three times (last night) and now wakes up at 4am.  Granted, it has only been less than a week, but nothing seems to work.  My DH has been home, but goes back to work on Monday, and then my mom will come to help. Each day one of us takes Sam out for an outing (I only have about an hour to spare as I am nursing) so that he can get our one to one attention.  We also have him be the "helper" for Ben but he wants nothing to do with Ben right now.  We have to watch him all of the time, of course, as he is rough with Ben right now.  As I write this, he is crying in his crib and it is killing me, but he NEEDS his nap.  Going in to soothe is making it worse.  I feel so bad b/c Ben being born has rocked his world, but how long does it take for the older ones to adjust?  Sam is only 22 months old, so it is tough to reason with him and explain.  We are really trying to let him know we are here and we love him, etc... any advice?  Thanks so much.  We are trying to keep to his regular schedule as much as possible, but no such luck.  With both of us home, and with the new baby, he is thrown.