Can Prozac make me worse?

I've been taking 40 mgs for a few years now and I recently ended up back in the hospital where they increased it to 60mgs. I haven't felt good the past week, my stomach hurts/nauseous and just felt very tired and blah. The past couple days i've always been feeling MORE depressed and having the suicidal thoughts return. Could this be caused by the increase in Prozac? Or am I just getting sick and going back into a depression?