What Causes Elevated THC Level?

hello my name is lashawn pearl and im currently in bhc health court and i did enter the program already positve for marijuana so they said they will test my thc level to see that it goes down. i entered the program 12-23-2014 around 12-27-14 i had hit a pices of weed and they called me in the office and said that it went up so i did admmit to using and they said that i need to stop now i have not been using and they have been testing me 1-02-15 throught 1-09-15 why is my thc level going up and down now that im not smoking