Suggest Tests To Confirm IBS And Crohn S Disease

I think I may have IBS or Crones disease after reading about the symptoms. I have had night sweats, some weight loss, and I am of European / Jewish decent among others. I get side aches and pain in the lower left side of abdomen and now the past week I have had the constant sensation that I need to have a bowel movement. Also painful lump at or just inside anus. pain lessens when I have a bowel movement and gets worse when anus is voluntarily constricted. I am 44 male, and had my last prostate exam at 40. Please advise as to over the counter remedies or possible treatment. Thanks