I am being treated for pelvic inflammatory disease and missed a whole day of my antibiotics. i also had to take a plan b today, will the plan b make the pid worse ?

Missing antibiotics for a day isn't likely to be harmful, but be sure and take the rest of your treatment on schedule. No worries about Plan B; it won't interfere with treatment. However, this suggests you have continued sex despite having PID. That's a very bad idea: it could be painful and because of reexposure (of you and/or your partner) to the STI causing your PID. Hold off a couple of weeks.