Hey, I had the exact same issue, found mine in the bath in my left armpit, got bigger and went away completely. My doctors said it was nothing to worry about; and until it went away I was constantly anxious about it also. My best advice would be to try to come to terms with the lump, remember that non cancerous lumps are very common, and in women especially because of many things. It could just be hormone changes or an infection in your lymph nodes, or a blocked hair follicle, or something that isn't so serious. I hope your doctor manages to find the root cause & keep your mind at ease x

theyll most likely do a blood test to test for any signs of cancer in the blood, heightened cell numbers or something, and they may even do an ultrasound (I had both) and it could genuinely just be a swollen lymph node, or a swollen sweat gland. Good luck I hope everything goes well, try not to google symptoms as it is terrifying. Hold out hope, and remember most lumps aren't harmful. I've heard that if you can move the lump around, there's less chance of it being something invasive, if that helps? x

Thank you, that's really helpful and reassuring! x