How do I know if I have been discriminated against due to my age?

I applied for reappointment to a position I held for several years with a past Supervisor. The new Supervisor hired a less qualified individual who is younger than me and put me in a "no title" position. That individual left for another job. I applied again and he said perfect. It came for re-appointment time and again he put an individual in the position who has no experience in that position and was just finishing training in a different position. I was placed in a position that became available early last year and is only part time. I was full-time. Due to certain circumstances when offered this current position last year I explained it is hard for me to make nightly meetings and it is part time and I was full time at that time. Again, the individual he placed in the full time position is a lot younger than me. Again, another position opened up he knew I was interested in and had several discussions regarding it. He hired a much younger person again. I am 50 years old.