My 10 year old has hlhs and high blood pressure, it has remained high like 176/104 or even higher at times, and he complains of right leg hurting, should i take him to the er? should i be concered?

A consultation: With your pediatric cardiologist is advised here. Any systemic symptoms and/or unusual, localized pain are most reliably addressed by medical personnel who have complete access to your child. Hopefully nothing untoward! best of luck!

Go to the ER : The elevated pressure alone is enough reason to go to the emergency room as there can be serious complications such as stroke. When it is combined with a complicated cardiac condition it is even more important to be seen now. I would consider calling 911 so that you can arrive safely and if there is any change in status it can be addressed immediately by trained professionals.

Yes: He probably needs more medications to better control his blood pressure, and also to make sure that he doesn't have obstruction in his aortic arch (coarctation of aorta) as the reason for his high blood pressure.

Yes: He should be evaluated by his pediatric cardiologist as soon as possible. If he develops headaches or other acute symptoms take him to the er.