You can do whatever you want. You can hold if you believe the price will go up again. Or sell all your coins and wait for it to go it's absolute lowest.
It's not easy to know when the price is at it's lowest but tokens usually bounce back. The good ones at least. Read up on the coin to find out.
Just about every crypto currencies go up and down. It's a normal trend. Bitcoin affects these as well so don't fall for the pit.