This could be a side effect of birth control pills.
It is important to get a hormonal status test, since changes in certain hormones may cause hypertension.
Hormonal disorders that may lead to hypertension are hypothyroidism, hyperthyroidism, Cushing's syndrome, an adrenal gland tumor-pheochromocytom ,excess secretion of a hormone called aldosterone.
Another thing is to make an urine test to check your kidneys function.
It will be a good idea to have a heart ultrasound and ekg test.
When hypertension appears in person with healthy lifestyle, an underlying condition should be considered.
Best wishes!
Marija