Swollen lymph nodes, fever, elevated labs (white blood count), infection, and mono are a few answers here.
It would be best to see a doctor for treatent. If it is in fact your spleen that is enlarged, this can be very serious and you would need prompt medical intervention. Maybe it's your gallbladder and not splenomegaly? Your description is quite general so it's difficult to even guess here. You really should see a doctor.
I saw a doctor a few months ago for symptoms that were quite like mono. They did the monospot test, which ruled that out. The doctor just told me to come back if it got worse (which it has), but I'm not going back to that doctor's because they don't seem to care about finding a solution.
I've gotten more symptoms, and some worse since then, but my parents won't take me back to a doctor, no matter what I say. They're convinced it's "all in my head" or something.
I'm kind of stuck in a rut here... what should I do?
(if you need a more detailed list of symptoms, etc, check my post in the lymphoma forum, "Could this be lymphoma?")
Sometimes monospot tests can come back inconclusive. You might want to ask your doc for an ebv profile. This test is more detailed and will also show if you have the eppstein barr virus. Good luck and keep us posted.