Hi, Smoking pot (cannabis) results in changes in the chemicals of the neurons, resulting in their effects on our mood and behaviour. When you suddenly quit smoking this substance, there is intense psychological craving in the mind for the same and the body and brain physically react to the absence of the drug. This is what is causing the irritability and low mood with heavy headedness. How is your sleep and appetite? How is your mood over days? Are your thoughts positive or negative? How do you feel about others? Are you afraid or fearful of them? There could be paranoid feelings, suspiciousness, even euphoria in such situations. I will suggest take help of a specialist/ Psychiatrist and get yourself properly managed for the same. I would have treated on the lines of Cannabis withdrawal and suggested Tab Baclofen for the cravings and Tab Olanzapine 7.5 mg every night for at least two-three months followed by gradual tapering.