What Causes Severe Fatigue?
Doesn't seem like a sensitivity to batteries
Detailed Answer:
Hi! Welcome to health care magic! Thanks for sharing your concerns with us and I would like to be of any help.
Based on the history you have shared, this tiredness and weakness can be due to sleep medicine your were using lately. It seem less likely to be due to any hypersensitivity response or allergies to batteries as you are not directly exposed to them. Batteries may contain heavy metals as ions and exposure to these is through direct skin contact or inhalations which leads to toxicity. There usage inside machines with such barriers in between is least likely to trigger any allergic response.
For generalised weakness and lethargy I would suggest you to undertake levels of calcium, vitamin D3, B12, thyroid function tests, blood sugars random, and other electrolytes like sodium and potassium. You can also start using supplements for D3, B1, B6, B12 and folic acid. These will make you feel better. If weakness increases many folds and interfere with carrying out normal daily life activities or movements consult a neurologist for detailed evaluation.
Hope this has answered your query, if you have any more questions, feel free to ask otherwise close the discussion. You can also reach me directly through my profile in future, in case of any more queries. Regards.