The features of low blood sugar (hypoglycaemia) fall into two categories. The first group of symptoms is due to activation of the autonomic nervous system and release of a hormone called adrenaline (epinephrine) caused by a rapid fall in blood sugar level. These include anxiety, nervousness, weakness, sweating, trembling, rapid heart beat (tachycardia), hunger, nausea and vomiting. The other category of symptoms is due to decreased sugar utilisation by the brain resulting in headache, visual disturbances, lethargy, lassitude, restlessness, irritability, inability to concentrate, mental confusion, somnolence, stupor, loss of intellectual ability, and personality changes etc. Your symptoms are very suggestive of low blood sugar level and you need to discuss with the treating doctor your diet and medication.