Prednisone causes inflammation side effect w/metronidazole & clindamycin. Cyst removed f. Gum. Why is ibuprofen not sufficient in place of prednisone?

Maybe not. I am not clear what you mean. Prednisone is an anti-inflammatory and does not increase inflammation. Ibuprofen has a slightly increased risk for bleeding because of antiplatelet effects I am uncertain what the rationale is for all your medications except that you might be infected or at risk for infection. Prednisone may decrease swelling but may also increase your risk for infection.