緊急求助：兒子在ER, Dr. gave him too much strong dose medicine and cause

緊急求助：兒子在ER, he had increased muscle tone, no seizure. but Dr. thought he had seizure and gave him too much strong dose seizure medicine and cause his very difficult breathing

The dose for adult is 2 mg, but Dr. gave my son 5mg within half hour. He had very difficult breathing, Dr. gave him medicine to stop his own breath and using respirator.
我心都快碎了。但是不知道如何和hospital去交涉，如何sue hospital.

我該如何處理這樣的事件，請好心的告知一下。