The symptoms you are experiencing could be withdrawal symptoms
(headache, fears) or flashbacks that usually occur after prolonged ganja (cannbis) use. The feeling of depression could be a result again of prolonged ganja use (amotivational syndrome) or else it could be related to a mood disorder
Stopping ganja use was an excellent first step. Continue to abstain and the withdrawal symptoms should disappear gradually. Because ganja persists in body tissue
this could take upto 4 weeks.
If the symptoms are interfering with your work and relationships you should consult with a psychiatrist
. This would help provide immediate relief and also address the important issue as to whether you have an underlying mood or other psychiatric disorder requiring treatment.