The word shedding is used loosely in this community. No one should consider shedding as a sign that a treatment works, anyone who tells you this is not giving you good information. The only way to know if a treatment is working is if you get results and this unfortunately takes time. Now, some treatments such as Finasteride and Dutasteride cause temporary sheds due to hormonal changes. This means the drug has effected your endocrine system however, it doesn't mean you'll be a responder and achieve hair regrowth. I am not familiar with minoxidil enough to tell you why a shed occurs, but never take shedding as a sign that a treatment is working. It's one of those things that you unfortunately have to go through before you know if you will respond or not.