What are the causes of tachycardia and low blood pressure? i.e 88/58 mm hg and heart rate 110 bpm

Hypotension: Your BP is not an unusual reading for a young woman. A heart rate at rest of 110 is also not unusual at your age but one would prefer to see it lower. Be sure you are adequately hydrated and not exposing yourself to exogenous stimulants like caffeine(coffee) or nicotine(tobacco).

Dehydration: The most common cause of combined low blood pressure and high heart rate would be dehydration. Anemia could also cause a higher heart rate, but not likely the low BP. Other less common causes might include hemorrhage or significant blood loss, abnormal magnesium or potassium levels. It is normal for the heart to beat faster when the blood pressure drops.