Altcoin follows Bitcoin because of supply, demand and speculation. It should be understood that the inter coin has a relationship with one another not to mention the currency market. As a trader just follow & exit before the price reverses direction. Indeed if at a glance confusingly where prices suddenly rise or fall, but there is a chance to make a profit. Try searching again about what causes the down / up is anything. Then use that knowledge to trade (fundamentally). thanks.