Are you confusing the thyroid with the parathyroids? They serve 2 different purposes - their only relationship is the location in your body and their names... Since you had your thyroid removed, you're going to have permanent hypothyroidism...that's a given. Without a thyroid there's nothing to produce the thyroid hormones your body needs.
You only have one thyroid gland that consists of 2 lobes and an isthmus. It produces hormones that control your metabolism, body temperature, heart rate and other body functions.
Most people have 4 parathyroids that reside behind the 4 corners of the thyroid gland. It's complicated, but to put it simply, the parathyroids control the way calcium is used in the body to control/produce electrical impulses.
If your doctor does not know that you will need to start on replacement thyroid hormone medication, such as Synthroid or some other type of medication, you really need to find a different doctor or you will soon be very hypothyroid...You will need to be on replacement thyroid hormones for the rest of your life, as we can't live, indefinitely, without them.
As for the calcium issue, it's possible that the remaining parathyroid can do the job, but it may take a while for it to ramp up. You will need to keep close tabs on your calcium levels.
Do you know what your thyroid hormone levels are, with reference ranges, along with TSH? If you have those, please post them, along with the reference range for the calcium level, since ranges vary lab to lab and have to come from your own report.
I might suggest you start looking for a different doctor, as well.