This research explores the causes and intensity of demand fluctuation and supply shortage of a supply chain (SC) occurred specially at the festival times. Management offers sales incentives & product discounts at festival times that sometimes create a complex situation to supply the demands properly. This complexity restricts SC performance and market possession. Hence, this research aimed to explore the responsible causes behind this complexity & bullwhip occurrence and claimed sales force incentives, number of echelons, price variation, quantity discount, & machine breakdown as the most responsible causes. Intensity of bullwhip effect (BWE) was measured by Fuzzy Inference System (FIS) of MATLAB TM to visualize their severity on SC performance. Few strategies have been proposed to minimize thier severity on SC excellence. Finally, this article proposed some managerial applications and guidelines to release the management from the frequently arising problems of distorted demands that will result in proper production & inventory management.