What Does A Mass On The Left Breast Indicate?

Yes
I was diagnosed with chondritus about 2 yrs ago by my OB.
I had a mammogram in November of 16 came back normal. On Christmas Day felt like I had strained my pectoral muscle from lifting hanging clothes, suitcase etc...
Went to Urgent a care on the 29th, gave me pretnazone and a muscle relaxer and he did a breast examination and said no concern and after completion to go back to my aleve 500 mg as needed.
Went back to SC to start packing up to move and continued to lift and down to unloading the u haul practically by myself.
Got worse strained more obviously....
Went back to Urgent care in Jan and saw another Dr. And was freaking out because it felt like A big mass in my left breast... He checked it and said I see you were here in Dec and said have you continued to lift since that visit... I said yes I have... He felt that area said yes I feel exactly what you feel it but again nothing to fear as your Mammo came back fine and it's not what your thinking... As my Mammo was in Nov and was Normal and this was Jan. He said that word I don't like to say doesn't grow that fast in 2 months... :))
He said the mass I felt was made up of fibrous tissues ,cartilage etc and I had really hurt my self and diagnosed it as lymphonitis
He said to do heat compressions and ice and it really helped!!! I have those beads that you beat in microwave and also deep blue rub. It has really gone down and feeling a lot better. That appt was on Jan 19
Tonight felt a little aggravated and put heat to it again and I raise my arm and feel and it still feels a little like something there.... Blood work in September all came back fine. It's something annual I have to do with my insurance anyway to get deduction off premium with Cigna.