Hi - Try scandishakes. They are used for patients with Cystic Fibrosis. They are high calorie shakes that you can make with milk. I have some for my mom and she says that they are actually pretty good. I know you can get them on line, but also have heard that they are sold at Giant Foods (like Safeway or Publix) in the Northeast. If you can get them there, they may be available in other chain grocery stores.
They work for my mom because she does not feel like eating much but now at least she is getting more calories in one shot.
Good luck.