Is it legal for my employer to not pay me (on salary) for a week due to excessive absence?

I am on salary at my job, which I have held for two years. When I first started, I was never told how many days off (sick, vacation, or otherwise) I was entitled to. At first, it wasn't an issue, but last year I ran into some personal hardships which led to my taking a day off every so often. I was never asked to produce a doctor's note and, at most, I was told in-passing that I was running out of days. The last time I was out was back in March, when I requested the last week off and it was granted to me. I have been paid as normal this whole time. Today, however, I checked my account balance and noticed I wasn't paid this week. When I inquired why, I was told that it was because my boss reviewed things and instructed payroll to dock my pay for this week due to excessive absence. Is this legal, especially since it is months after my last absence? If not, is there any legal recourse I can take?