This is perfectly normal. Prices do rise and fall. On 2014, the year started with bitcoin's price at $758 and that same year ended at $320, a 58% declined. Afterwards from 2015-2017, end price of bitcoin flourished year after year.

This year 2018, bitcoin started at $13,860 and now currently (as of this writing) $5366, a 61% declined. However, I do believe bitcoin will be able to recover and its value will increase multiple times in the coming months and years. Patience is the key right now.