We very recently lost our GSD Rex, who was only 9years old, very fast and mysteriously, we think it was a reaction to vaccine.

We were heartbroken.I looked up a local sheperd rescue to donate our food to, and we discovered Valor. Both the kids and I were drawn to him. We are a good dog family, and since we will grieve our Rex for a long time, we decided it was not "too early" to give another dog a home. We decided to adopt Valor two weeks later.
He has been with us a week now. He is a great dog. BUT...he came with undisclosed medical stuff (not by the rescue, but the current owners, the rescue was the middle man), and a very long story.
He was throwing up daily and getting Pepcid to remedy the vomitting

What I cannot seem to curb is the shedding. He sheds immensely, and is very itchy. I have ruled out fleas. We brush him, and i have to sweep or vacume several times a day. It is only a week, so this may change, but the hair is driving me crazy.
Any recommendations?
Thank you.