If you hold any type of license, i.e., nursing license you may want to make sure you are not going to be reported to the Nursing Board. When you spoke to your Human Resources Director were you asking about the process for drug testing or how you were treated? If you actually were complaining about harassment then then the Human Resources Director should be conducting a confidential investigation. It just seems like in your question there are a lot of issues going on, drug testing, harassment/hostile work environment, discrimination. You may be able to get on line and look at the EEOC website to find out if what is happening to you falls into any of the categories of discrimination listed on their website.
This answer is offered as a public service for general information only and may not be relied upon as legal advice.