Worth repeating that this is not medical advice and the answer often depends on who you are.

You are not imagining it and you are not being difficult. Document it and take the document in.

Interdose restlessness is distinct from the original symptom and worth naming separately.

Same here. Nausea on an empty stomach was my main issue with sulbutiamine too.

Ten percent cuts, of the current dose not the original. That is the arithmetic that keeps it survivable.

Do you contact the customs office or the carrier first?