My cat was nuetered 2 days ago, and i noticed some changes, shivering while sleeping not cold shivering it is like nerve shivering, lack of apetite,shows no intrest in playing, sad mewing. Sleeping too much and he became afraid and following me everywhere he became so affectionate. I just need to know whats wrong and if he is going to be ok he is 1 year old and mated twice before surgery