I'm pretty sure the Ibuprophen is only for the pain........it won't slow down your period, if anything, it will increase the flow.
Yes, I've had the same weird symptoms..... sometimes early, sometimes very late, twice I skipped it altogether and very clotty. My gyno said it was premenopause so that's what I had been thinking. Several years ago I had a procedure to check the lining of my uterus and they told me because my body wasn't making enough of ... oh, I forget whether it was estrogen or progesterone... I was getting a built up of tissue, hence the clotting.
I'm at the right age for menopause, but if you're younger, I'd go to my gyno first. Maybe if you describe your symptoms, they could work you in right away. Anyway, good luck and let us know what you decide to do.