Is it legal to retaliate when a grievance is filed??

yesterday i made a grevance regarding an issue at work.after i did that i was told by my manager to clock out and go home, which i did as i was instructed. upon going 2wk 2day i was informed that i had been taken off the schedule.(the shift mngr told me and she had no clue of the events that went on the day be4 until i told her). over the phone, the manager to me as of today i was terminated.(i know that in texas its not legal to terminate someone over the phone). but my main question is is retaliation against employee filing a greivance legal (in texas)? (also i was informed by the shft mngr. that i had no write ups of any kind in my file. october wouldve made 2 yr employment 4 me and that she didnt understand y she terminated me.) ive filed an unemployment claim is there any thing else i should do?thanks in advance