Intestinal flora symptoms and conditions

I am a 42 year old male who was put on a 600mg 21 day course of Omnicef along with 7 days of Prednisone for a recurrent sinus infection. Augmentin had failed and Avelox was a horror show. After 10 ten days of virtually no side effects I am now totally constipated and bloated to the point my pants don't fit. Also my stomach is constantly rumbling and gassy. I should add that it has done ZERO for my sinus infection. I have been taking pro-biotics everyday. I am now afraid to eat anything and scared of using an enema as I might kill whatever beneficial intestinal flora I have left. It seems to me that besides the "old standards", the new line anti-biotics are just evil. Unfortunately doctors and most Americans over prescribe and over use anti-biotics to the point where we now have to rely on these harsh new drugs. Stop using anti-bacterial hand washes!! Soap is just as good!

A confirmation - I also am having very loose, watery bowels, going to the bathroom frequently. It's killing all the normal intestinal flora (hence the watery feces) along with my persistant bronchitis. My lungs feel better, but my abdominals are upset. Definitely reaching for the Acidophilus when my course of antibiotics is over.