Thank you for your query.
You have not mentioned the duration of the pea-size lump and whether it is increasing in size ever since you noticed it. These information shall help in my guidance of the case.
If the doctor was not able to give a definite conclusion on the ultrasound
then the best course would be to repeat the ultrasound after 2 weeks. If that remains inconclusive then an excisional biopsy
may be required.
I hope I have answered your query to your satisfaction.
Wishing your daughter all the best.