How much compensation should i get?

I recently went to pick up my prescription from my pharmacy. It was mental health medication. The box said the right name with right tablets on. Inside how ever different tablets. Which i took for six days and this made me ill as coming off mental health tablets suddenly is not good. Giving out wrong drugs is surely wrong and also the locum must off not checked it before dispensing. This is surly dangerous. People are saying i should get compensation. Should i and how much if so. Thanks