Am suffering from fever since Sunday. I initially have P. Vivax positive but the day before yesterday it was normal. I still have fever which is no less than 100 and it increases at intervals. Paracetamol is also not working. What can be the exact reason? I am feeling extreme weakness and I sleep as soon as I go to bed. To walk and to work for more the half an hour have become very difficult. Are there any other tests to find the exact cause of my illness?