don't worry
immunology is not all that tough. but if u look at it like it is, then it may as well be. try to understand the first few chapters that are the core chapters. dont waste too much time memorizing what are ALL the cytokines released by every single type of white cell. just memorize n learn what are the main functions of each white cell. then FA n kaplan will highlight the most important cytokines released by these cells n what they do.
also understand the diff between chronic n acute inflammation reactions. this will help u in answering questions (ie, increased lymphocytes, or increased neutrophils, etc) which will lead u to clues about the disease, etc. tackle it slowly n calmly.
also memorize the hypersensitivity & autoimmune diseases. once u've done plenty of questions u will eventually remember the case presentation of the diseases. then it'll be all ok. the beginning is always tough but it gets easier.

try again. good luck.