You would have to work 10-12 hour days of brutal labor with poor nutrition and not enough sleep to overtrain in the way you think you might be.
Overtraining applies a lot more to bodybuilding than to endurance sports like BJJ. Overtraining in bodybuilding means that you are not giving your muslces enough time to grow before putting stress on them again. But you have to remember that bodybuilding is something artificial that we put our bodies through for looks, not performance. Endurance activities are what the human body is naturally built for.
You are only doing 6 workouts a week for a few hours a day, this isn't that bad. Your body is adjusting to a new work load, and you can definitely handle it. If you eat properly and sleep 8 hour nights, your body can handle an incredible amount.
There's a lot of fail going on in this thread. BJJ is not an endurance sport. Overtraining can manifest in a variety of ways in almost every sport. A high rep/low weight routine, while it won't make you stronger, can increase your muscular endurance, your ability to deal with lactic acid (and pain), and is often a good pre-strength training phase for periodization.
I don't know why some people would hop in this thread to offer unsolicited S&C advice when they don't know the TS's goals. Especially when this unsolicited advice comes arm-in-arm with a bunch of other bogus information (see "BJJ is an endurance sport" above).
TS, it's very difficult for us to tell if you're overtrained or not. If you're having a hard time coping with the pain, I would back off a little bit and see if it gets better. Play with your routine and see what works for you. If you can't find a good middle ground, you might want to see your PCP and get some help. Good luck.