I'm not terribly concerned, but I did talk with my grandma who I live with. She has a panic button thingy. If anything really serious happens we can get emergency help.
I believe you may be right about the zonked part. If it's a stimulant, then I'll rpobably be more hyper and zonked at the same time...not a really good combo. I think it will be more of an inconveniance than a serious threat. That's why I posted about it rather than calling the doctor right away. if things get too worrysome, then I'll call the doctor or have grandma call.
Never on the tabs you mentioned. But I doubt 2 would be enough to OD on. You may just feel twice as zonked ( out of it ). If you have any real doubts ring your local doctor. He / she will give you full peace of mind and be able to tell you if you should need to do anything at all. That should always be step 1.