Long Dan Xie Gan Tang question

In general terms you don't avoid an herbal formula (or individual herb) because it is "too cooling", "too moving", etc. you choose an herbal formula that is exactly what your diagnosis in TCM terms dictate at a given point in time.  Even what has worked before is not always a great indicator of what will work for you now.

In more practical terms, Long Dan Xie Gan Wan is in the "clear heat from the organs" category.    So if your diagnosis supports heat clearing, then you should use the formula that is correct for you.  Dosage, of course, also plays a large role in the discussion.  If a little long dan greatly alleviates your breathing/anxiety issues, then I wouldn't worry about taking it for a awhile.  That said, the point of Chinese Medicine generally is to try to resolve issues to the point where treatment is no longer necessary and this is only possible by not only being incredibly accurate with the initial diagnosis in TCM terms, but also by (in many cases) changing formulas over time as the underlying situation improves.

For you, in very general terms, it sounds like your breathing issues are related to anxiety - but anxiety can come from "heat" in tcm terms, from digestive issues in both tcm terms and western terms, and from purely psychological issues so to speak that can arise even when the underlying digestion, etc. are functionally well by most accounts.  This is what the role of your practitioner is - to try to determine the root of your issues and provide ongoing guidance for you to resolve these issues.  It cannot be generalized.

Now all that said, to not leave you with anything, if you have a red tongue with a yellow tongue coating and other physical signs that are appropriate for long dan xie gan wan, then by all means consider it.  Xiao yao wan and related formulas from the "regulate and harmonize the liverr and spleen" category would be too mild (and functionally incorrect) for someone in many cases who truly had heat signs.

What might help you is one of the more predominant formulas for what we call "plum pit qi" - Yue Jue Wan - possibly combined with Xiao Yao Wan.  But that is something that should be discussed with your current (or a new) practitioner who can physically inspect you and discuss your health issues openly.