I Would like to know if it's legal for an employer to take away your sick days and dock your pay because of being out of work for a week with a work ingury?

I burnt my hand at work and got 2nd and 3rd degree burns on my hand and my doctor took me out of work and labled me as 100 percent disabled for that week. I was paid my salary for that week but now 3 weeks later my employer took away my sick days and docked my pay because they said I shouldn’t have been paid for the week I was out due to a work Ingury. I work for mcdonalds and would like to find out if this is legal and what I should do.