A 103 deg fever is a pretty good indication of a bacterial or viral infection. In other words, you got a bug. Get plenty of rest and do what the doctor said. Forget silly things like fasting or fruit diets. Depriving your body of necessary nutrients is not a good way to maintain or improve your health.
Foods like lemon juice don't "detoxify" your body. The liver generally deals with toxins. Unless you are eating rat poison, you shouldn't have any mysterious unidentified toxins that need to be "cleansed" by some herbal potion. That's BS quackery. Just eat right and get exercise when you start feeling better.