Does this sound like a brain tumour?

Im 18 and used to be a very healthy, happy outgoing person. Now I am always tired, weak, sore, my muscles and joints are stiff and sore, I get major headaches, ear aches and pain behind one eye. I have lost about 4-6 kilos and my appetite and thirst have increased.I get nausea and stomach pains. My skin is extremely dry and very very itchy. The doctors have no idea whats wrong and the symptoms are getting worse. Please help me. I have come looking on the internet as a last resort! I am also experiencing mental dullness and have stages where I just space out. I get dejavu alot.
I have been tested for ross river, had my blood count, iron and alot of other tests done and they have all come back great.
Please help me.

[russtoo]

Hi;

   You sound miserable, Carlizia.
   Could this be thyroid related? Have you been tested for that?
   I hope you have access to Endocrinolgy.
   Not sure if you've had a lot of stress in life, but Fibromyalgia fits some of your sx.

   Russ

[Carlizia]

Thanks russto. Im only miserable becuase i feel so off colour and cant figure out wats up. Yeah the doctor said i may have thyrotoxia. thanks for your help =]

[missnevaeh]

Dehydration could be a reason

[Carlizia]

No. I drink about 2 litres or more a day... Im always a very thirsty person