Thyroid and GBS/CIDP
While many of us have both thyroid problems and GBS/CIDP, it is highly unlikely that thyroid problems are a residual effect. Nerves don’t seem to play too much of a role in thyroid activity.
How much do you know (and are willing to share in public forum) about your thyroid numbers? I assume that they actually tested you for the amount of TSH (thyroid stimulating hormone). If that number is low, it means that you are producing too much thyroid hormone. An overactive thyroid leads to loss of sleep and a high metabolism. If it is high, you are producing too little. An underactive thyroid reduces your metabolism and leads to fatigue and possibly neurological symptoms.
Are you taking any medicine for your thyroid issues? If not, I assume that the TSH number was borderline and they want to see if it repeats. If so, then they will be looking to see if the TSH number moved into the normal range. They should be able to tell after 6 weeks, though, not three months.
Godspeed in sorting out the thyroid issue.