Hi and welcome to the forum
The red in the eye is blood and it's from a physical injury (the fish swimming into something). Clean water usually clears it up.
The water in the tank looks milky cloudy and that is usually from uneaten food and a filter that hasn't established yet. The best thing for this is big daily water changes and gravel cleaning the substrate. That is also the recommendation for the injured eye.
I can't see any white spot. Where are the white dots?
Melafix doesn't treat white spot. You need Malachite green or copper to treat white spot, assuming the fish has white spot. Make goldfish develop breeding tubercles (small white dots on the pectoral fins and gill covers) when the weather warms up in spring and summer.
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BASIC FIRST AID FOR FISH
Test the water for ammonia, nitrite, nitrate and pH.
Wipe the inside of the glass down with a clean fish sponge. This removes the biofilm on the glass and the biofilm will contain lots of harmful bacteria, fungus, protozoans and various other microscopic life forms.
Do a 75% water change and gravel clean the substrate every day for a week or until the problem is identified. The water changes and gravel cleaning will reduce the number of disease organisms in the water and provide a cleaner environment for the fish to recover in. It also removes a lot of the gunk and this means any medication can work on treating the fish instead of being wasted killing the pathogens in the gunk.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.
Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Wash the filter materials/ media in a bucket of tank water and re-use the media. Tip the bucket of dirty water on the garden/ lawn. Cleaning the filter means less gunk and cleaner water with fewer pathogens so any medication (if needed) will work more effectively on the fish.
Increase surface turbulence/ aeration to maximise the dissolved oxygen in the water.
