Thank you for your query.
The cramps are normal after Mirena insertion.
i think it is more likely that you had mild gastro enteritis
that has now passed off.
Mirena is not known to cause nausea and diarrhoea to this extent, that too merely 2 days after insertion.
sometimes, the hormone progesterone
which is the active content of Mirena, could rarely cause this.
Anyways, since you are better, it hardly matters.
If the problem recurs, consult your healthcare provider.