1- Hyperthyroidism: or over active thyroid gland (meaning the thyroid gland is secreting excessive hormones). Symptoms of hyperthyroidism include tremors, heat intolerance (feeling hot even when the climate is mild), nervousness, loose stools/diarrhea, protruding eyes (on the long term), and increased appetite/caloric intake without adding in weight, or even with weight loss. We can detect hyperthyroidism by testing the level of thyroid hormones (thyroxine  or free T4- elevated, plus thyroid-stimulating hormone - decreased) in blood.

2- Hypoglycemia: or decreased blood sugar level. The symptoms of hypoglycemia are episodic, meaning, they occur in episodes during which the blood sugar falls below 60 mg/dL. Symptoms include tremors (shivering), sweating, dizziness, nausea, and sometimes headache and near-fainting. The diagnosis is made by taking a blood sugar level using a glucometer during the episode to document a low blood sugar level - if this is the actual case, this warrants further investigation.

3- Fever: if your body temperature is elevated because of an infection, you may experience the above-listed symptoms.

4- Anxiety attacks: also known as panic attacks, these physical symptoms, including tremors, diffuse sweating, palpitations (fast pounding heart beats), a sensation of chest tightness and/or pain, shortness of breath, are the result of acute and severe stress, so the physical symptoms are the result of something purely psychological.

I recommend that you visit a general internist or family physician to get a good physical examination and thorough assessment to identify the underlying cause of your symptoms.