I think my pekingese just ate a multivitamin+iron. Should I be worried?

I heard my dog chewing on something in my room and I wasn't able to fish it out of her mouth in time. In the area I saw a few multivitamins and I assume there was a spill that I didn't know about or something. The vitamins contain 18mg iron as well. Should I be worried? Is there something I can do? Money is tight, and there are no vet clinics open nearby. Am I overreacting?