Hello, I have gone through your query and understood the concern. Infections can often disturb the hormone balance and interfere with the menstrual cycle. Also, the medications used for treatment, especially the antibiotics, are another cause for menstrual disturbances. Home pregnancy tests should be done 3-7 days after the missed period with a fresh early morning sample. The blood test is a better method as it is more specific and sensitive. You can go for that. A trans-vaginal sonogram also is helpful to know the status of the pelvic organs. Hope this helps.