Taking ibuprofen 800mg for swollen gum until i get teeth pulled, have been cutting it in half & taking with food & water. i noticed my lower left back hurting only when i lift something a little heavy. is this related to med or is it a normal strain?

Maybe coincidence: The usual dose for ibuprofen (Advil, Motrin) is 400mg orally every 6-8 hours, either as needed or for several days. It relieves inflammation and pain, so generally makes one's back hurt less, not more. One's primary care doctor can take a look to see what's going on with the back. Meanwhile, one should lift using only the proper, safe lifting techiniques.