Hi, welcome to our site. I am Dr. Kalpesh Kavar, MD. Read your query. That is a very significant question and i appreciate your problem. I will try my best to answer your query GENERIC PLAN B which is emergency contraceptive which can cause some side effects like Nausea, lower stomach (abdominal) pain, tiredness, headache, dizziness, and breast tenderness. The side effects remain only for few days, but like you mentioned you have taken it a month before and you had your menstruation on time which suggests you had a successful contraception. If you still feel your stomach hard and have a consistent problem, then it needs to be evaluated. I would like you to consult gynecologist and get youself examined and if required some investigations including USG abdomen to find out the cause. But I can tell you it should not be because of contraceptive pill. I hope this helps you. I have given you the answer to the maximum considering the information provided. Please do understand that some details could be extracted from a detailed history and examination. Please feel free to ask another query. I would be glad to help you. Looking forward to your return query with the details asked so that I can help you further. (If the answer has helped you, please indicate this) Take Care.