Its a tank in cycling.
The much to high nitrate you have measured supports that because the tests show much to high value when nitrite appears. The measured nitrate value will go down when the nitrite will get lower.
The clouding looks like being bacterical. You could by a nitrite test to have a closer look on the value but when the measured nitrate value goes down it will be because less nitrite.
There are 4 things You can do.
1. Reduce feeding to 20% of what You feed today. The fish will do good for a while with less food and it will be much less nutrition for the bacteria.
2. Add more live rock. Live rock not dead. That gives bacteria more surface to settle on. Dont clean side and back windows for a few days. Thats bacterial settlement area too. Real live rock has much more porousity than rock mined on land. 10% of the water volume is the optimum for most tanks.
I know there are many tanks with less stone and dead stone but they are more difficult to keep in balance.
You are a beginner now not an expert. You will learn more and more so maybe You will be one in the future.
3. Make a 20% water change to get the phosphate value down. 0,12 is not a very high value for a small tank. Its just a high value that can be lowered with some waterchanges.
4. Wait. Dont add anything new to the tank. Dont add UVC. It will slow down Your cycling.