eye infection

my son, 15 months had eye infection a week ago with high fever. we tried breast milk AND cammomile tea. which helped a bit, by than gave him eye drops (chloramphenicol, english eye drops). we gave it for a week, after few days he had shilshul for few days. his beter now AND this morning suddenly woke up with an infected eye after two days we finished the treatment. what does it mean? the virus is still there? because we gave according to instructions. he wasn't intouch with any children this week. do you recommended to start again with the eye drops, as we don't like the idea its antibitocs.. Toda