What Causes Irregular Periods After Using Clotrimazole Vaginal Suppository?

hi doctor,well i need to ask you a question regarding the clindamycin n clotrimazole vaginal suppositories.well,after using this suppositories i am having menstrual problems.I use to have my period on either 09th 0r 10th of every month,but after using this product i did not have my period on time.So,i am bit worried!!!Is it normal and nothing to be worrried at.please help me. Thank you