New lumps 2 months after exchange surgery

Hi! I originally posted in the recurrence forum. I'm very high risk for recurrence and the tumor was 10cm at its largest, less than a 1mm margin after mastectomy. I was stage 3 triple negative, diagnosed June 2017. Had 4 months of chemo, then double mastectomy November 2017. Then 6 weeks of radiation and then oral chemo (Xeloda). Just had exchange surgery at the end of November 2018.

They felt okay at first. The cancer side felt a bit firmer, as I was warned it would due to having had radiation.

Within a month of the exchange surgery I felt a small lump and luckily already had a follow up appointment with my oncologist. The lump felt exactly the way my original tumor felt, and my cancer grew FAST, from pea sized to 6cm in just under 4 months. My oncologist felt it too and noted it as a small palpable lump of several millimeters between the rib and the rim of the implant, in the same spot as my original tumor.

She sent me for an MRI and to see the breast surgeon (I actually saw his nurse). The nurse also felt the lump and sent me for an ultrasound. She said if it was fat necrosis, ultrasound would be able to definitively say so. None of the imaging saw the lump at all. The radiologist told me “There's nothing there."

That was just over 2 weeks ago.

I asked how we can all feel the lump but imaging didn't see anything at all. I was told it may be a suture from surgery and I should check with the plastic surgeon. So I call and the PS is out on medical leave. His PA checked his notes from my surgery and said no suture is noted in the area in question and they'd have to see me to be sure. So I have an appointment next week. (But I don't really feel the plastic surgeon will take it as seriously since they're not cancer doctors.)

NOW that lump feels bigger. I also now have either two small lumps or one large lump (hard to tell) in my lower armpit right where the breast meets the armpit. This was NOT there at all when I had the MRI/ultrasound.

There just seems to be an awful lot of lumpy areas for a “breast” that had a mastectomy and should have very very little actual tissue left behind

The whole breast also appears to be retaining fluid or something because yesterday morning I woke up and had “pillow creases" on it, just like you sometimes get pillow creases on your face when you sleep.

Dealing with unknown lumps after having a mastectomy is frustrating. Especially when imaging showed nothing and now just two weeks later, the first lump is bigger and there's lumpiness in the lower armpit now too.The BS's nurse told me fat necrosis or scar tissue would show up on imaging and wouldn't grow. But is she right? Can scar tissue or fat necrosis get bigger over a few weeks and start popping up in the armpit area also a few months after surgery?