16 year old male with high blood pressure?

All my life ive had normal blood pressure, but last month for my physical my BP was 160/80 so my doctor was concerned. Ive gained about 20 pounds in the past 6 months and havent been very active because i did not play football. Since i had my physical ive been eating very healthy and conditioning for baseball(very strenuous...worse than hell week for football) I sometimes take it at the nurses office at school and its usually around 145/80 I went back to the doctor today and my bp was first 135/75 and then 146/79. Shes concerned i guess so she took blood and is sending me to a cardiologist, and putting me on BP medication. She also wants an ultra-sound on my kidneys. What could this mean?? Should i be worried??