Tweezing is the worst way to remove hair and distorts the hair roots (makes them curve and can even make them tougher and more resilient). This could maybe account for the trouble your electrologist had killing the hairs. That doesn't excuse it though, she should have adjusted her technique for curved/distorted follicles. A better electrologist with good equipment can handle hairs that have been previously tweezed without trauma to the skin. Don't give up just yet.
The only reason (that I know of) that your pigmentation would worsen at this point, is if you get more ingrowns and they irritate the area. So take James' advice and be sure to minimize any future ingrowns. The pigmentation you have now shouldn't be permanent. It will fade (slowly) as the traumatized skin gets replaced by new cells. You can speed this up with a retinol (though that will dry you out even more for a few weeks). or use kojic acid or another skin lightener as Dee suggested.
3.5 laser sessions on lower legs starting 09/24/09 (GentleLASE)
3 laser sessions on bikini starting 01/15/10 (GentleLASE)
1 laser session on underarms starting 07/02/10 (GentleLASE)
1 laser session on right arm starting 07/02/10 (GenteLASE)
6.75 hrs electrolysis on tummy starting 01/07/10 (Apilus Platinum, picoflash)
10 hrs electrolysis on arms starting 01/30/10 (Apilus Platinum, synchro/picoflash)
37.25 hrs DIY electrolysis on left arm (OneTouch and Instantron)
1.75 hrs DIY electrolysis on tummy (Instantron, thermolysis)