First of all I will start by saying I have a bizarre job... testing for the medical proffesion. I work 12 fifteen minute tests with a ten minute break inbetween each one.

Two days ago on a break I was doing situps ( like I have been doing for two year) and the center director approached me and said I could not excercise, I asked why, he then SCREAMED while hovering over me and shoving his finger in my face " BECAUSE I SAID SO THATS WHY ! "
The next day I was called to the office and said i was getting put on review for poor performance. In the 2 years i have been there, getting monthly evaluations, i have NEVER gotten scored below a 90 out of a possible 100.

There have been 8 other incidents like this with other employees in the past week. Most recently He told one employee who was speaking Spanish that English was the only language to be spoken. Two employees that have filed complaints with HR have been fired.

What would be appropraite action, is there anything i can do??

Nothing you have described suggests that anything has occurred for which you have legal recourse. Screaming at you with his finger in your face may be unprofessional but it is not illegal. If they feel your performance is currently below standard they are free to have your evaluation reflect that, whether you agree or not and no matter how good your previous evaluations may have been.

The only thing in your post that even MIGHT violate the law is the language question, and depending on circumstances even that might well be legal. It is not illegal to require English be the only language spoken with regards to work issues, though the employer cannnot limit what language is spoken when the employee is on break or otherwise on their own time.

If I am injured at work do I have to go to a doctor that the company wants me to go to...or can i go to my doctor?
I was also told that I would not be able to return until i had medical clearance, no mention about workers comp. I am a Part-time as needed employee.

You must go to their doctor, unless you filled out a "Pre-designation of Personal Physician" form prior to the injury.

Workers comp would cover the injury if it is work related. You should speak with your HR department for further assistance with filing the claim.

Once injured, your company is correct in its insistence on obtaining medical clearance to return to work. No one wants you to further injure yourself by returning before you are healed (for both common sense and legal liability reasons).