The symptoms, such as brain fog, twitches, irregular heart rate, shortness of breath, anxiety attacks, leg weakness resemble Covid Long-Haulers' or Covid vaccine Long-Haulers'. The underlying cause is small fiber neuropathy and autonomic neuropathy and possibly microclots in the lungs. However, if it's the vaccine, side effects would usually either be immediate or begin within 2 weeks. Often people with adverse neurological reactions to the Covid vaccines are those who previously had autoimmune conditions, as in your case. If you would like to learn more, the Neuro V Long-Haulers Facebook group is a great source of information.