Worried about a lump under my breast, awaiting clinic appointment

Hello, just looking to share as feeling concerned.  I previously had a cyst removed from my breast some years ago now and had a clear mammogram 3 years ago.  I am 54.

4 weeks ago I noticed a 5cm lump on my chest wall under my breast just below bra line, 2 weeks when and saw my GP, a locum and got referral to breast clinic (not had appointment yet).  Lump is irregular in shape, not moveable and appears to be turning grey in colour and you can see it quite clearly, it is very visible not just touch.  Not sure but think I had another as well which I can't see but feel a bit further along.

Now I am concerned about some other things going on with my body, I have been dieting but had rapid weight loss without trying,  extreme fatigue always, no energy for anything and night sweats.  Also, been getting very hot daytime as well. Sometimes feel sick with the heat. Got back pain, knee pain and had flu like symptoms.

Just anxious.  Has anyone experienced same and then had cancer diagnosis or all clear?