Dried Discharge in Bra & on Top, Mostly on Left side. Hormonal?

Hi all, I wanted to post to get some feedback from others that might have a bit more of a clue on nipple discharge matters.

I've never - that I know of - had nipple discharge before. (I'm 29).

So, just before Christmas I went to the doctor about migraines and she decided to put me on a different Pill. I'd been on the same combined Pill since the age of 16 and now I'm on the mini pill. The good news - so far - is that it's been 3 months and I've not had a migraine (Just the odd lighter headache). But what I did notice a short while after changing to the mini pill was that my nipple - specifically my left side - seemed to be more sensitive to my bras. There is a seam that goes diagonally across the cup on the inside and if I bent over and it rubbed on it just slightly it would send a strong sensitive feeling through that nipple/breast.

I then noticed a small circular patch inside the bra where my nipple would be that kind of looked like a patch of dry skin had rubbed off and had made the material feel hard/crusty.

At one point, I don't know how or why it happened - maybe hormonal - but my left breast became painful, red and swollen. It did go down and back to normal after about 4 or 5 days though.

Then 2 days ago, I noticed a strange, dried, dark patch on my top about an inch round in size that had also made the material harder. I checked my bra and it was on there too. It could only be nipple discharge as I've not spilled anything on myself.

I keep feeling and checking now and then to see if I can feel/see any discharge actually coming out but there is never any when I do. I try applying pressure and lightly squeezing but nothing comes out.

I can't really tell what colour the discharge is because my bras are black and the top was maroon.

Today, I'm not sure if it's just in my mind now, but I feel like my left side feels a little hot in the breast and under the arm.

I thought it was just on the left side but upon close inspection I can see a couple tiny spots of dried stuff on the right side too, but hardly anything compared to left side.

Do you think this could be happening due to hormonal issues from the change of Pill and perhaps the rubbing against the bra seams, or possibly some other issue and that I should get it checked out?
Many Thanks in advance! x