Underarm pain & Breast Pain - Im worried and need advice

Hi ladies, first time posting here though have been reading a lot. I'm 38 yrs old and for the last 5 years have had some sort of swelling/thickening feeling in my right armpit. I had an u/s which was negative at the time. This feeling has occurred on and off now for the last 5 years. It was really bad this past Jan and I had another u/s down which showed normal. Fast forward to this month where again the pain is bad and I see my gyn who sent me for a mammo and u/s - showed normal. Since the mammo, about 2 weeks, ago I have had breast pain, arm pain (very bad at times), and underarm pain. The feeling that it is swollen or thick is still there and some times it feels like something is in there pinching me. I just got home from seeing a breast specialist and he doesnt want to send me for an MRI even though I asked for one based on my symptoms. He just wants to see me back in 6 months. But I have this pain and I have no idea what to do next? Can anyone give me advice? Do I see another specialist and demand an MRI if this continues? He mentioned it being fibrocystic breast tissue but Im not convinced.

The pain has gotten worse over the last 2 weeks, then it subsides a bit and then it gets bad again. Im so scared this is IBC although no lumps can be felt or found. The pain is mainly in the arm and arm pit down to my elbow and I feel it in my breast every so often. Please help! Thank you!