Considering that all the tests have come back fine, you are not undergoing a relapse of any kind. It is worth mentioning that antibiotics are administered only when you face a bacterial infection and not a viral one. Perhaps there is some misunderstanding about the illness or the medication. Viral infections usually do not make a comeback immediately after one infective bout because the body’s immune system has already identified the specific causative organism and accommodates for a certain degree of change in viral forms. This is a mechanism that is called adaptive immunity – the reason why you can only get some diseases once in your life like the measles. Bacterial infections would also not come back as fast but relapses can sometimes happen; however this would also not happen immediately. The most likely problem is that your kidney is still not fully healed from the trauma that it faced and therefore the radiating back pain that is symptomatic of kidney disease. The first thing that you need to do is to visit the doctor and undergo more detailed kidney function tests to ensure that everything is fine.
Dealing with kidney infections or a malfunctioning kidney is a major problem because, just like the heart, the kidney does not stop functioning at any point of time. To understand how the kidney performs its filtering activities think of the kidneys as a sieve so fine that if you poured tea in one end, water would come out of the other end. The human body is always creating toxins that need to be excreted and therefore, the kidneys never really get a break from regular work.
Assuming that the problem lies in the kidneys doing too much work, you have to reduce the concentration of heavy metals in the blood and limit the intake of any toxins. This means that you need to restrict your diet to very basic foods for some time. Stay away from protein for the time-being as excess protein and purine is broken down into uric acid, which will overload the kidneys. Stick to a carbohydrate diet with no flavoring or salt, though sugar is allowed. The one thing that you can use for taste is wasabi, which has diuretic properties. Drink lots of water and eat a few bananas a day to retain potassium levels. Finally, apply a cold compress, a few ice cubes wrapped in a towel and rolled over the aching region, over the kidney area.