We got a scare a couple of years back when our teenage son got an eye infection - the doctors and eye hospital went through five different antibiotics before finally finding something that fixed it, which was quite stressful. NB When you are warned not to wear contact lenses in swimming pools - take it seriously! We're almost certain that's how he got the problem.
Were these soft or hard lenses? The one time I had to switch to softs, I had an infection in 2 weeks. My lens hygiene procedures are not compatible with softs apparently.
He had only been using them for a week or so and wasn't that good at getting them out so I suspect he must have scratched his eye while getting them out after swimming.