How long does the fever last?
Do you have chills and tremble during the fever? How does the fever subside - spontaneously or only after tyou take medicines?
Have you been travelling lately? WHere ? To any tropical country?
Since when have you had this thrush infection? Since the fever started or even before?
I believe that you are suffering from Malaria - the symptoms you describe, especially the type of fever are typical of the disease. Since you have returned from Mexico where malaria is very common, it is possible that you were infected there. Please see here for more of the symptoms of malaria - scroll down to the symptoms and signs of Malaria.
I think the thrush in your nouth is a result of the weakening of your immune system by the infection. Possibly you are also anaemic. Please apply a candid mouth paint inside your mouth thrice daily - this is an OTC medicine available at any pharmacy.
You will need to see a doctor for a check up and to get your blood examined for the presence of malarial parasites as well as for anaemia.
I hope this helps.
Let me know if you need more input. If not, please click on the green"Accept" button on this page. A positive rating and adding a bonus will be warmly appreciated.