Is it my race or my age, and if so could I prove it?

I am a white woman in my 50s working as an administrative assistant for a large nonprofit, where several of the senior managers and a large number of the staff are black. I am also one of only 3 people over 40 who did not enter the organization as a middle or upper manager. All 3 of us boomer age support workers are white and we are all classified as hourly non-exempt, while there are women running around half our age who are constantly getting promoted. The agency is very youth-oriented and very "rainbow", and I feel out of place as a middle aged white person. The young woman who sits behind me is 30, blonde and gorgeous and has recently been promoted to a senior management position even though she has only been there two months longer than I have and I have basically the same or better credentials. Until she quit six months ago, the middle manager in my own department (I'll call her Donna), a 50-ish black woman, used to regularly exclude me from meetings, withhold juicy projects from me, talk trash about me to her direct reports behind my back, and demean me in public. We shared the same boss, a black male, who let her basically run things and never did anything to stop her inappropriate behavior. Once two years ago he approached me about taking a new position that would amount to a promotion, if he could get it funded. I said I would be very interested. Three months later during the funding effort, Donna succeeded in taking the job away from me and giving it to her 26-year old protege. Since that time I have unsuccessfully applied for two other positions within the company for which I had more than the minimum qualifications. In both cases, my application was denied in favor of people in their twenties and early thirties.

My boss's boss (let's call him Ron) is an older white male, and both my boss and Donna used to spend the first half of our weekly staff meeting trashing Ron behind his back, both for his micromanaging and for being a clueless white dude. On one occasion with my own boss's support, I met with Ron to call him on some negative behavior of his own. My boss proudly reported this to Donna and the rest of the staff. Donna's reaction (I'm paraphrasing) was to say she would never get an apology from Ron, but of course I can get him to apologize- just look at what color we both are. I objected, but she is the kind of person who will never let anyone else have the last word.

I am dying to get out, but our health benefits and fringes are superb, and as a single person I can't afford to leave until I find something that will sustain me well. I have been applying for all kinds of things but haven't landed anything yet.
Meanwhile, if I find legal counsel who feels I have experienced actionable discrimination of one kind or another, I would consider a suit against the agency. Thoughts please? - Is this your question? Add additional information