Lots of good info above – but contact lens wearers get some interesting and different problems, particularly acanthoemeba keratitis and the like. You may still end up needing to see a Hospital Eye service…
Don’t put your contacts back in till you have been 100% better for at least 48hrs. If they are non-daily disposables, chuck ’em. If you still have problems in 48 hours from now on the drops you got, do seek help, and do so sooner if the vision gets worse in the meantime. Try reading small print with the affected eye. Other symptoms you should take seriously include a feeling like there is something stuck on your eye, blurring/fogging/haloes around things you see, and pain which appears to be in the eyeball itself.