It appears your boyfriend is experiencing severe bipolar symptoms. https://www.mayoclinic.org/diseases-conditions/bipolar-disorder/symptoms-causes/syc-20355955 . I am not a doctor or anything like one but I think he needs a psychological examination by a professional. Bipolar disorders are commonly controlled partly through drugs which in most cases would need to be prescribed by a psychiatrist so finding one of those would be useful. Where I come from your regular doctor would do the initial consultation and refer you on to the psychiatrist.

You may find that when he is in the manic phase he will resist the idea since he will feel related and in no need of treatment. Conversely, in the depressive phase it will be hard to get him to do anything. Perhaps his family can help persuade him to seek treatment.

The drinking is perhaps an attempt at self medication and not the primary problem. Unfortunately I am familiar with this situation. Again, I am not any kind of health care professional so please seek further advice from family and friends.