I hate to sound mean but none of those fish are compatibe with that size tank, except the goby. Your fish probably got ich from being stressed. You need to get a qt tank and begin hypo. You will also need to run your dt fishless for weeks to get rid of the parasite. If you use meds in your tank you will kill all of your corals.
You wont have to medicate if you do hypo in qt tank. If you medicate your main tank you will kill your inverts and coral. You need to get rid of some of your live stock and run your display tank fishless for weeks.