Terminated for got injured at work. - Spareboard Labourer Weyerhaeuser Employee Review

When I Started my job in weyerhaeuser while working I got back back injury and ask for day off to get some rest or visit doctor instead of giving me off from work they said you have to come at work and continues 4 days without any day off with pain they write a termination letter on 5th day and in letter they didn't mention anything about my injury. They only find negative things of my work but I was in pain they expect me to fulfill work they want. They promised me if you work continuously we will put you on easy work but nothing happened. Last day I was working on weekends that is not included in my regular schedule manager gave me letter of termination. He is trying to be smart.