Until you've had the tests you shouldn't change your diet (unless, of course, instructed to do so by your doctor or perhaps if the problem might be related to obesity).
There are many types of liver disease. One of them, for example, is haemochromatosis, where excess iron builds up around the liver. People with that condition need to
reduce their iron intake, so eating liver (which is rich in iron) is exactly what the should avoid doing!
This link provides a good starting point for finding information about liver disease. However I suggest simply bookmarking it for future use, so that you'll know which section to read once the medics are able to put a label on your condition:
http://www.nhs.uk/conditions/liver-disease/Pages/Introduction.aspx