Well you either took 50mg worse scenario, or 25mg best scenario. Um, if you have no opiate tolerance I would err on the side of caution and wait (don't fall asleep) for about 4 hours forthe drugs half life to expire and you'll be fine. If they were only 5mg pills you'll be completely fine. Kick back end enjoy one of the most carefree and easy highs you will ever experience. You may feel a little bit itchy or nauseous - normally I'd say take a benedryl, but if you don't know your dose I would avoid it (increased CBS depression and all that). You won't die and I doubt you'll want to get locked up in a hospital for a week minimum (it's pretty damn hard to get chocolate milk in the big house).
Don't worry, you'll be okay. Just stat awake for awhile. As long as you haven't had tons of alcohol, benzos (anything ending in Pam or am) you're no where near the red zone