Why do I need another ultrasound after biopsy for thyroid nodule I had an ultrasound ten days ago?

No. Not unless there has been a significant clinical change or another biopsy is required. Repeat biopsy will be necessary at intervals to evaluate progress and possible therapies.
Not common. It is not common to need another ultrasound 10 days after a thyroid biopsy. I would ask the physician who ordered the study why you would need another ultrasound so soon.