Thank you for your query.
node enlargement on one side can be due to some abrasion in the scalp
of that side which may have been overlooked. In case the lymph node increases in size or becomes painful then we need to worry otherwise it should be re-examined after 2-3 weeks.
Pain in the hip and knees and headache off and on needs to be evaluated for the cause. It can occur folloiwng a viral infection but it shall be better if you get your daughter examined to know the exact cause.
I hope I have answered your query to your satisfaction.
Wishing your daughter an early recovery.
Rajiv K Khandelwal