What Are The Side Effects Of Plan B?

Hello Before starting birth control I was regular with 25day cycles. I went on birth control for 3 years. Came off a year ago, had spotting during the first month(which I believe is normal). The 5 days prior to my first period off the Nuvaring I didn t spot. I had my period like always. The next month, the condom broke so I took Plan B. Ever since then my cycles are average 29 days. I also have spotting starting cycle day 24-26 continuously until my period starts. On average 7-4 days of spotting(Brown, sometimes stretchy) up until period. My husband and I have started to try conceive with no luck. Last month I had big black clot during my period which is not normal for me. Please, what do you think it happening to me.