Since you had your wisdom teeth removed I'm guessing you've been on a liquid/soft diet and on pain pills. Medications can lower your BP as well as resting. Low sodium can also cause low BP. 90 isn't low enough to cause major issues (passing out), but it can make you feel lousy. Since your peak is 105, there's no harm in adding more salt to your diet; if you're still on soft food try soup broth.

Low blood pressure causes Faulty nutrition, Malnutrition The most important cause of low blood pressure is faulty nutrition. It makes the tissues forming the walls of the blood vessels over-relaxed, and flabby or streched. This results in less supply of oxygen and nutrients to the tissues. Malnutrition can result from a diet deficient in calories, proteins, vitamin C, or almost any one of the B vitamins. Loss of blood, slow internal bleeding Sometimes the blood pressure falls rapidly because of loss of blood. Low blood pressure may also develop gradually because of slow bleeding in the gastrointestinal tract, kidneys, or bladder. Emotional instability Emotional problems are a far more frequent cause of low blood pressure. To a lesser degree, prolonged disappointment and frustration may result in a subnormal blood pressure.

it's not really low for your age and weight, completely normal! just eat properly

Are you taking pain pills? Are you laying down a lot?