What Are The Side Effects Of Rivotril?

Yesteday night my sister (20 year old 42 KG weigh) has mistakenly taken one tablet of Rivotril 2mg (Clonazepam). Since she took she is feeling dizziness and sever pain in legs. At the moment she is fine but she can not walk on her feet. Please advice right medication. I consuted with a local doctor. He said he can not understad the problem.