Should I go back?

Hello all!

I'm a 24 year old female living temporarily in Japan. On July 9 I noticed that my right breast was noticeably bigger than the left and felt very edematous but not painful. I was a little worried but thought I'd watch it and see if it went away. It only seemed to get bigger and started hanging more to the right side so I asked my bilingual coworker to go with me to a breast specialist on July 26. I had a mammogram and ultrasound but, while the doctor admitted that it was bigger than the left, she didn't see anything and that was the end of it.

I thought alright the likelihood of me having anything serious is really low because of my age so I'll trust the doctor that it's nothing.

However on July 30, I got a very sharp sudden pain in my right armpit and I've since continued to get pain there as well as develop pain in the upper outer portion of my breast. The size has increased a little bit as well.

Should I go back to the specialist? It's not as simple as if I was in America and could just go to the doctor myself. I have to ask my coworker to come with me to translate and I'd rather not put her out if it's nothing.

Thank you for taking the time to read this!