Dehisced mastectomy wound

I haven't experienced anything like that. My wound was slow to heal completely, but even so, the process only took about 3 months. I think you should ask to see your surgeon again, and tell her/him you need to have something done about it.

Not with a mastectomy wound. It did happen to an appendix scar when I was about 13 though. It split half open and was infected (the surgeon said it was because he had removed the infected appendix through the scar that the scar itself got infected.) It was about a 2.5 inch split and took about three months to heal completely. 

I agree with AP7 - ask for a referral  back to your surgeon. This operation is traumatising enough without the added stress.