WC ageed to cover treatment for my injury for life. Now they have gone back on their word.

They have now decided they do not have to continue my care because a random drug test failed to show the medication (Percocet) I was taking in my urine. I have found article after article about drug testing for oxy drugs (which is what percocet is)and how urine is NOT the most accurate way to test for these drugs, but blood should be used. I have articles from several Forensic Laboratories; Sports Team Labs; etc. I have requested a hearing about this. CAn they just stop covering my treatment for this reason? I took my meds the morning of the test at 5:30am (like I did every morning for years) and they took my urine at 12:40pm. Over 7 hours since I had taken a dose. I worked for this employer 10 years, 7 of which were AFTER the injury and was never out of work. I do not have an education and I dread having to go stand before this commissioner and try to plead my case alone. I can pay some, but how much would someone charge me for this? I can''t pay alot.