Thanks for your question on Health Care Magic.
I can understand your situation and problem.
Since your cardiac work up is normal, no need to worry for heart diseases.
Sometimes,
skin infection of nipple and areola can cause
cellulitis and tenderness.
Hormonal imbalance is another possibility cause.
There are certain changes occur in breast tissue if patient is having hormonal imbalance.
So in my opinion, you should
consult dermatologist and rule out skin infection.
Consult gynecologist and get done hormone levels to rule out hormonal imbalance.
If all these come normal than
anxiety can be the cause for your symptom.
First diagnose yourself and then start appropriate treatment.
Hope I have solved your query.
I will be happy to help you further.
Wish you good health. Thanks.