Calcium & Thyroidectomy. I do now?

Hi Doctor, I had Total thyroidectomy on 28th February , 4 parathyroids were preserved, DAY 1 after surgery my Calcium was 8.6 . DAY 2 my Calcium was 8.3. I was told to take Calcium supplement with vitaminD3  3000mg/ 3 tablets per day for initial 1 week. Later dosage was reduced to 2000mg , 2 tablets per day. I had 100mci of Rai therapy on 31st March it went well. Post RAI Since 3 days I was told to take up 1 tablet per day 1000mg at night.Dosage was reduced because I dint had any tingling sensation in hands and legs post surgery till date. After 3 days of low dosage intake i.E 1000 mg per day I had a recent Serum Calcium blood test in which calcium was 7.0mg/DL . It's more than a month my surgery over, after surgery calcium was 8.6 Why did calcium decrease now after a month  ? What could be the risk factors? What should I do now ?