Hello Diego,
Unfortunately no one here can diagnose what condition you may have as there are several reasons why you may be constantly thirsty.
A couple of problems which spring to mind is Hyperglycemia (high blood sugar) or Diabetes.
Of course there could be other causes which are easily treated.
I must advise you to got to your doctor and get the problem investigated and diagnosed. The quicker this is done the quicker it can be treated.
Below please find a couple of links which should give you more information.
https://www.healthatoz.com/healthato...rt11072006.jsp Diabetes Symptoms
Good luck and I hope it is nothing too serious.
Cy
(Poseidon)