Hi jcrane. I do recommend you consult a gastroenterologist. It is possible you could have IBS or it could be an IBD. Unfortunately, we all present with different symptoms in different combinations, so it is hard to tell you much. I know I had no blood and no weight loss before I was diagnosed. I did have terrible constipation and pain, but it was written off to "the family has always had bad tummies". Make an appointment and start getting evaluated...it is not fun to live in pain and not know what to do! It's not a ton of fun if you get diagnosed either, but at least you can start getting some answers and hopefully relief.
Take Care