Multiple Eye Infections after 1 month.

Hi, I had eye infection started around two months ago. When I was driving bike, suddenly my right eye became red which was already suffering from dry eyes (both eyes). One day later, water started coming from my right eye. When I went to doctor he prescribed moxofloxacin, but I got no relief. 2 days later, I again went to same doctor, he diagnosised me with keretits+ conjectivitis with few mild spots on cornea. On 7th day, I started facing blurry vision and went to another doctor. Je prescribed moxofloxacin + loteprednol (0.5% each) and an artificial tear. But still my bluriness was increasing. One week later, my vision became totally blurr at morning (6/36), which was slightly improving at evening. After checking, doctor found too many small dots on cornea and prescribed dexamethasone 0.1% + moxofloxacin 0.5% and continued artificial tears along with with. I got near to normal vision witthin one month. But the infection came back after 2-3 weeks. Why this happened?