Aiyoh mama, that little cough after fever is quite common lah, but since baby dah kurang senyum and quieter than usual, better check with your doctor just to be safe, post-fever cough can be normal recovery, but the change in behaviour needs a proper checkup to make sure everything's okay. A few of my mum friends' babies went through the same thing, and it turned out to be just the tail end of the infection, but don't take chances lah, go see the doctor for peace of mind!