I was waiting for your reply to my info request.
I would advise to go to ER for an examination.
Shallow breathing, pain can be due to inflammation & infection of pleura.
Pain under right breast & shoulder can be due a gall bladder pain too.
Gall bladder pain can be referred to right shoulder.
But with shallow breathing you need an urgent examination by doctor & tests.
X ray, ultrasound examination, blood are likely to be necessary.
I hope this information helps.
I will be happy to assist, if you need any clarification.
Please feel free for any follow up query.