You might be needing some digestive enzymes, it may have been that you didn't have enough to digest the fat. Enzymes with your meals would also do a lot for irritable bowel syndrome.

Sounds like rancid oil to me. I take fish oil but not in capsules because you can't tell if it's rancid in the capsule. Rancid oil is really bad news and will cause diarrhea. I know you probably just bought them so they shouldn't be rancid but it's hard to say how long and where they were stored before you bought them.

I take fermented fish oil - which I would think would also be easier to digest. It's not the most enjoyable 10 seconds while taking the spoonful but it's not so terrible. The key is to chase it by sucking on a lemon or lime wedge - kinda like when people take a lemon drop shot. I'd take a shot of fermented fish oil over vodka any day 

Here's the brand and flavor (or lack thereof) that I use and highly recommend...
http://www.greenpasture.org/retail/?t=products&p=products&a=display&i=1088

It also really helps to take the fish oil at the same time as a meal. I get sick to my stomach sometimes if I take it too far away from food.

I think I had the worst reaction. I had chest pains from taking fish oil. I thought I was having a heart attack.  It was a serious GERD reaction.

Heart problems are the number-one killer of American men and women, which is odd considering that heart problems were an uncommon cause of death at the beginning of the 20th century. While it's true that more people died of infectious diseases in those days and often didn't live long enough to die of , they also consumed much greater amounts of long-chain Omega 3 fatty acids found in fish oil. As subsequent generations began eating less fish and more beef, their rate of heart problems shot up.
Fish that contain the highest level of mercury are larger and older sharks, swordfish, king mackerel, and tilefish. It is probably a good idea for most people to avoid eating much of these fish. They can be replaced with other fish and shellfish such as shrimp, pollock, canned light tuna, salmon and catfish, which all contain much less mercury.