My right testicle has sudden tenderness and an achey feeling after waking up. what does this mean?

Just watch the symptom for now. You can take tylenol or apply cold pack for the tenderness if needed. If pain gets worse next day with tender and swollen testicle +/- scrotum, you should see your doctor by then. We, sometimes, may have transient pain at different body location with unknown cause.

If it is swollen and tender pl see your doc or Urologist rightaway for without exam a diagnosis cant be made