Mood swings can occur commonly when a person is stressed. We as human beings use several different defenses to avoid the unpleasant thoughts or situations. Your avoidance of the studies could be one of the methods of coping with the stress of studying. However, it's maladaptive as it doesn't help you in the long run. The reason for your stress needs to be elicited and dealt with in a pragmatic approach.
Next Steps
A Psychiatrist would help you out in these difficult situations by giving you clarity of thoughts. Please consult a Psychiatrist.