Re: Discrimination - Am I too late? Is Union culpable, too?

I am a 44 year old professional female, a Union member, working for a major well-known corporation. I work in a male dominated field and women are outnumbered by men 4 to 1 at my location. There are 10 people at my location who perform the same job, 9 males, and myself, the only female. I don't make widgets, (does anyone?) but for the sake of analogy and argument my dilemma is this:

When I began here 7- years ago I worked the worst shift, and was more than likely being paid less than everyone else, regardless of experience. That intial discrimination aside, I continued on, happily producing widgets at an admirable rate for the Company for the next two years until, one day five years ago, low revenues forced a rare shake-up which involved me and - I believe four other men. I was seen as the one who was benefitting the most, being moved to a prime, important shift, bumping a man, in an effort to boost lagging production, although I'm pretty sure my slick company was careful not to call it a "promotion". Still, it was by no means punitive or negative- while the other moves were either lateral and /or obvious demotions, and in fact my two bosses were bumped down a notch, one of them back into the bargaining unit. This "recognition" of my abilities actually resulted in a pay cut for me! of about 5-thousand dollars a year! (A similar move would not have had a negative effect on any member of the Shop but me, I later found out, which showed I made the least.) I thanked the company for the recognition but pointed out the paycut, and was basically told, (paraphrasing)
"Shutup and be greatful for your great shift". My male dominated Union, could have cared less, too, and did nothing. Stupid me, I let it go, thinking the company was probably perfectly in its rights to be jerks and there was nothing I could do. End of story?... except that I am just now finding out that the none of the MEN involved in the shuffle, including those who were demoted, lost a single dime in salary, and only I was so taken advantage of! In fact, the demoted manager still has his company car to this day, the only member of the bargaining unit who does! Only an actuary could figure out how many tens of thousands of dollars that little company maneuver will cost me over the course of my employment here. I know there's a statute of limitations on disc. claims, but I feel I'm being discriminated against with every paycheck I will continue to receive until the Company makes me whole. They pulled a major fast one. Did these good 'ol boys outsmart me since I didn't find out right away that I was being dissed? Also, is my Union in anyway culpable? They should never have allowed this to happen. And do they have any obligation to supply me with information I need to determine whether this is, in fact, the case? They say they don't know what the manager was making who's now a Union member. Should I even believe those idiots? I'd hate to think I'm up a creek just because they managed to hide it so well. If you do think I have a case - who should I see first - a good lawyer, Corporate,. the Union lawyers? (who, by the way, already seem like they're scared of a lawsuit from me.
Know any good emp. lawyers in Philly? Please feel free to leave names. Thanks.
Thanks for all your help...