Re: sudden tiredness
Yes, it could be from your anxiety causing GI (gastrointestinal) problems. GI problems are also related to chronic fatigue which seems to be what you're getting. Medications can also cause tiredness and I remember you being prescribed propranolol - so that could also be a factor if you're still taking it.
You should find that these problems subside as your anxiety improves but in the meantime I find that mint tea helps with the stomach problems.
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KK
Never Surrender, Comrade