4m old (pterm 2ms) baby eye movmnt.

Hi, My 4 month old baby (7th month born) having cold and fever 4 days back. So some antibiotic,fever,cold and cough medcne prescribed by doc. After taking these medcne for two days baby started crying in night ,trouble in taking feed. Now taking feed but sleeping too much also when awake doing wiered eye movement. He keeps his eyes open wider than before.But follows the object with wider open eyes. Also getting irritated very frequently and going to sleep again and again.also now stopped cooing and smiling. Medcne prescribeb and taken for 3 days- phexin . 5ml,Tminic,calpol(.5ml),ascoril ls .5ml 4 days before these medcne he was prfactly normal, cold and fever started and these medcne taken for 3 days.now no fever but cold and cough still there. Please tell about this change in behavior after these mdcens. Thanks