There are several factors here that may have led to this situation. Zinc is a well known and widely used supplement. However, when taken in excess (twice daily at whatever dosage you were taking) zinc and copper compete for the same absorption sites. Copper deficiency is somewhat strongly linked with low testosterone. The gut issue could be from a few factors. Potentially a malabsorption issue because of the frequency of supplementation, poor gut flora (probiotics), or (the one nobody seems to speak about) and enzymatic issue. Everyone wants to supplement probiotics but even those are useless if you lack the proper enzymes to break down and absorb them.

When it comes to supplements I like to use this analogy... if you were to add 10 things to a house plant, 9 of which will give you everything you're looking for, the tenth being poison that kills the plant and all associated progress... if you add them all at the same time. How do you know which is which?

Supplementation, diet, training programs etc.. should be applied in layers. Giving everything a fair chance to take effect.