Ok I Was Taking Metronidazole Started Taking It On 12/31/15

Ok I was taking metronidazole started taking it on 12/31/15 I got my menstrual on 1/06/16 I went off my menses on 01/11/16 keep on mind I'm a be patch user so started my regimen back on Sunday 01/10/16 I had unprotected sex 01/12/16 and I hadn't finished my metronidazole so I took a pill on 01/12/16 forgetting I shouldn't have being I wear the be patch so should I take a plan b pill would the pill metronidazole interfere w/the plan b pill