"Sudden rise" refers to something that quickly goes up, increases, or becomes more popular or successful without prior indication or anticipation. Full definition
The fish are dying because of sudden rise in temperature. (hubpages.com)
This relatively sudden rise of normal sea level occurs when storm winds and tides combine to transport large volumes of water to coastal areas. (waterencyclopedia.com)
It would be difficult to say if the tweet had an impact on the price drop but given the very sudden rise in price, it is no surprise of a correction. (crypto-lines.com)