Keflex and ribs

I finished a 5 day course of 1000 mg a day over a month ago. About a week afterward, I started having sharp pinging pains in the "bend" areas of where my colon is. Painful gas and bowel movements, and blood in the bowl. (not in stool) Also have had gum pain and mouth ulcers. My intestines feel blistered. I'll be ok a couple of days when eliminating, then suddenly a bowel movement will be followed by bright red blood and tissue. Very scary. I am taking Acidophilus, trying to eat carefully and drink only water, nothing harsh or citrusy. I have pain on the left side of my gut mostly. Under ribs, at waist and very low left side. I'm afraid, but then, this is a harsh drug and I do not have fever, have not dropped weight, lost appetite, or felt weak. I just feel like my insides are shredding and ulcerated. I will NEVER take this again. It's odd, because I have taken it before, for much long than this. I refused to take the last 2 doses the former time, because it literally tasted like fertilizer smells when i would belch after a pill. Vicious drug. I am watching myself and my issues, and hoping I don't have to have further treatment and that I have not totally ruined my colon beyond repair.