Advil effects on menstruation

Has anyone had their cycle reduced due to.taking advil ? I've noticed over the years that it reduces mine so i try to stay away from them while im menstruating but i do occasionally need to take them. I usually have my flow for 7days but if i take advil it'll reduce it to 3 to 5days instead. This time i had my cycle on 5-12 to 5-16 and now today when i went to clean myself i noticed dark brown on the toiletpaper. I know its old blood but im getting very bad cramps down there. Was wondering if any other ladies have gone thru the same situation. I lost my Mom 5.5yrs ago and have no one else to talk with. TIA