When my boyfriend first tried weed about two months ago, he had a bad trip and ever since then he’s been having flashbacks to the bad trip and is having trouble concentrating, eating and sleeping.
He even had a few panic attacks when he was reminded of the bad trip.
He’s in a very dark place and traumatised because of the trip. I don’t know how I could help him.

So my question is, are his mental problems a product of the bad trip or did marijuana somehow cause him to “activate” his anxiety. 
Did this ever happen to you and so, how did you overcome it? Should he see a therapist or should he just wait as time passes on and forget about it?

Any help appreciated!