HELP, Constapation, too Nexium, can i take Pepto Bismol?

I have taken Nexium an hour ago because i thought it might help with my constipation, I have a painful bowl movement, the stool is hard and small, it also floats on water. Can I take Pepto Bismol now, to counter that effect, because I keep feeling like I have to go to the bathroom. HELP!