Report with a formal complaint the lab who did the parasite examination of your stool specimen and failed to find ova or mature flukes to your state's Department of Health. Be sure to include ample documentaion of your contraindicating evidence that you really do have flukes and/or the eggs that the lab failed to find or identify. When the DOH investigates, it's not very pretty - I've experienced it! They send experts in the field of laboratory Science to examine every process, procedure and record in the lab. The original stained slides, which are required to be archived by the lab, will be examined by independent parasitologists. If you're lucky, you can supoena the state's investigation to use in your malpractice suit against the lab. Good luck!