I think I was fired by retaliation, now where to go.

Location: Texas

At the beginning of July of this year I was bit multiple times by a dog while at work (I work for a boarding facility) that required stitches, multiple rounds of antibiotics and was out of work for 3 weeks. This was covered by Worker’s Comp.
During my time out I went back and forth about getting an attorney against the owners of the dog. I didn’t know i could have reported this incedent to OSHA until that deadline has already passed. After looking over and over my employee handbook and the dog’s repeat aggressive history I decided to go forward with my decision. This is due to the owners lack of important info regarding medical conditions and previous bite history at home. The dog did have 3 other attacks at my facility (not including the one that sent me to the ER) and one at a sister facility. No one reported any of the previous bites to the proper authorities (at the dog’s home he bit at least 2 other people). I told my manager that if she didn’t, then I would, so the dog was finally reported. Corporate tired to tell her to wait and see what happened. The owners did not like this and were angry with me.
I let my managers know that I obtained legal counsel against the dog owners and NOT my employer and they were understanding and let HR know. When I returned to work, my manager had a long conference call with the owners of the dog who were very irate about the attorney. A few days later I was called into my managers office to a conference call with the District Manager. At first everything was pleasant. Him stating how much my manager and the Company love what I have done for the facility, my work ethic and what customers have said. Then he states that I am being let go because of the route I am taking by hiring a lawyer. That the legal team doesn’t want to be left open for a lawsuite by the owners if I am still employed by them. They need to protect their own. I was not given written termination documents, even asking and emailing HR multiple times for this and my employee file.
My manager did not want this outcome and fought HR. I have been an exemplaryemployee, always went above and beyond what my job required because I absolutley loved my job. Because of this she and the assistant manager are leaving their employment.
My question is: is this legal? I know Texas is “at-will” but from my research this tactic is nefarious. I have been trying to get answers. What type of attorney would I need? Any advice would be much appreciated.