Thanks for your query.Based on the facts that you have posted it appears that you have grade one Varicocele
You have been taking drugs as apart of treatment for varicocele .
To be true there is no medicine for treatment of varicocele.
The reduction in the sperm count
after stopping the treatment is a coincidence and should be taken as a normal variation, and as such a count of 58 millions is within normal limits and you need not worry at all.