I had a friend with the same problem as you and they took her gallbladder out to no avail. She STILL had pain!!!
A nurse friend asked her if she was given a Mono test and she said she had alot of blood work done. When she contacted her doctor's office, they told her that they HADN'T done a mono test.
I would think with an enlarged spleen, you could possibly be looking at mono. It doesn't necessarily have to make you tired. But it can make you VERY sick.