Is there still a way to sue after signing a settlement agreement from previous employer?

I’m in need of some help with a wrongful termination, harassment, and discrimination case against my previous employer, I belonged to a union and followed all the steps along with grievances complaints. They offered me a settlement in return of an signed agreement contract not to sue. But I felt pressured and forced to sign it as they rushed me into it before I was able to speak with a lawyer. I need advice and help if I can terminate the terms of agreement for the settlement money I got and sue instead, as I have also filed an EEOC complaint which they are ready to file the complaint against the company .