Pregnancy and age discrimination

Upon my return from pregnancy leave, I was told by my employer (a large Customer Service Promotional Company)that they were taking me off my sales accounts and giving the accounts to a much younger male employee that did not have as much experience as I had. Additionally, I was forced into searching for a new account. This action caused me to lose all my sales revenue. I then proceeded to construct a business plan and make new contacts for this new account as requested. I was told that I did a great job by my immediate supervisor and given the "green light" to pursue the account. The day after I submitted the busines plan to my employer with names and contacts, my immediate supervisor walked into my office and fired me on the spot. No written or verbal explanation or review were given to me prior to this action. My immdeiate supervisor told me that I was being fired because of "poor sales performance." How could I achieve any sales when upon my return from pregnancy leave , they took away my accounts and therefore how was I to achieve any sales? I was asked to leave my office,TURN IN MY KEYS AND LEAVE THE BUILDING immediately. Do you think I have a discrimination case?