Thanks for the query.
The possible cause for your problem are:
-Side effect of mirena
due to humidity sometimes can lead to itching.
So if the symptoms continue, once consult gynecologist and get examined.
If she recommends you can go for mammogram
Tablets containing eveningprimerose oil can help in revealing breast symptoms due to hormonal effect.
For more details you can ask me through: http://www.healthcaremagic.com/doctors/dr-sree-gouri-sr/63429