All these are common signs of many diseases. Flu like symptoms can be seen for diseases such as cholera, typhoid, jaundice and many others. There is no way to say for sure what this could be. But my guess is that it's just the flu. If you have a stomach bug then this might also cause symptoms like this. Its probably something that you ate or drank. If there is a problem with your stomach then you might be facing a long stint in the toilet. But it should clear out in a day or two without any issues. Cheers!