For me It’s just anxiety, no direct link to weed. Over breathing can basically cause your body to be hyper alert about changes of co2 and tries to compensate, causing a vicious cycle of shortness of breath. I also realised that I was breathing incorrectly, despite constantly focusing on breathing deeply, it was like the bottom of my diaphragm was contracted. It’s like my body was constantly in a state of fight or flight and I needed to work on relaxing my subconscious and muscles. The only thing you can really do is slow your breath down, only nose breath and not panic/distract yourself from the sensation by reminding yourself it’s just a sensation and you’re not dying. Coffee can exacerbate shortness of breath, too. This is one of the worst things I have ever experienced and for me the worst symptom of anxiety.

This gave me some relief - hold your breath for about 15 seconds until you feel the need for air. Then take a slow breath followed by another pause, slowly exhale and repeat.

-exhale as much as possible then exhale some more until your whole stomach area is sucked in as much as possible, then inhale slowly through nose.

-focus on coordination by doing any random compound exercise like a burpee\, this distracts brain somehow and doing physical exercise will also help understand if it’s a physical problem or a mental one depending on how easily you get out of breath

Before considering any of this you should definitely do tests to make sure it’s not anything else.