After i stopped taking zinc supplements, my hair suddenly thinned, started falling out, and my mustache became patchy. should i resume?

Of course: Zinc deficiency is relatively common. A common symptom of zinc deficiency is hair loss. The fact that you experienced this after stopping zinc is highly suggestive that you are now deficient. Taking zinc is perfectly safe and very likely to prevent further hair loss and may even help some to grow back! see http://calosol.Com/zinc.Php.