Oh boy i saw this once when i first started getting into fish. Popeye is as Pharaoh above me said that you must have a high ammonia content in your tank. All fish keepers should have basic water testing supplies. I only have two (ammonia, and pH tester), and out of those i only normally use one (the pH). When I got popeye on my JD (coincidentally the same fish), i did research and found out ammonia is the main culprit.
I immediately did a 50% water change and a 25% water change each day after this for the next 5 days and the condition disappeared. I almost lost him and that was a wake up call for me. Now i do 30% water changes on all 5 of my tanks twice a week on Wednesdays and Sundays. The tester that i use is the pH tester because different fish like different pH levels, and my ammonia tester is just collecting dust because frequent water changes, proper amount of food given, and constant gravel, sand, vacuuming keeps my ammonia as well as my nitrites and nitrates at 0 ppm.
Also before i forget, if you have a heater in the tank, drop the temperature and allow the water to cool because the cooler the water, the less dangerous the ammonia is on the fish. As far as what chemicals you should get; I will tell you what i tell everyone. . . "Only get what you need to regulate pH and add beneficial bacteria, unless your fish are sick and need antibiotics or melafix, frequent water changes is all you really need. I rather do a water change, than add chemicals."
Your cloudiness is probably due also to the overwhelming of bad bacteria to good bacteria ratio, again as a result of too much ammonia. A week or two of daily water changes should make the cloudiness begin to dissipate. If you have any questions, feel free to inbox me.
