I am part of the 3.078 trial for GBM. They give my Anktiva shots on alternating sides every two weeks in my abdomen. After the shot, I get some redness at the injection site the next day. It is also itchy and a little sore for about 4-5 days but then it clears up. I've never had a flare-up like you described. The pic below is the "average" reaction that I get.
I am sure everyone experience may be different.