Hello and welcome to Healthcare Magic. Thanks for your query.
It is bery unlikely that any OTC medication can result in a positive test, specifically for cocaine. It is also unlikely that your medical conditions can be the contributory factor also.
However, it is possible that any test can have a false positive result. There have been reports that certain anesthetic
medication like lignocaine can produce a false positive result. If you strongly feel that the test results are incorrect, then I would suggest that you take up the issue with your doctor for a detailed discussion about how you can proceed further.
Wish you all the best.
Dr. Jonas Sundarakumar