My period is about four days late, but Ive had some light spotting (not enough to need even a panty liner). I took pregnancy tests that all came out negative. Now I have a fevor and a pain in my left side.

You should seek a doctor immediately. You could have a cyst, pid, or an ectopic pregnancy. This is serious! Don't wait around! Take it from someone who has been through a ruptured ovarian cyst and emergency surgery, see your doctor!

You should seek a doctor immediately. You could have a cyst, pid, or an ectopic pregnancy. This is serious!! Don't wait around! Take it from someone who has been through a ruptured ovarian cyst and emergency surgery, see your doctor!!

Can you explain what those things are?

An ovarian cyst, is just that, a cyst on one of your ovaries. There are several different types, and most women get them and never even know it, they just go away on their own during their cycles. But sometimes they can grow and twist the ovary or rupture, spilling the fluid contents into you abdominal cavity and causing a lot of pain and risk of infection, resulting in surgery to remove the tissue.

PID-pelvic inflammatory disease, is an infection of the uterus, fallopian tubes, ovaries and reproductive organs that seriously damage the organs and result in pain and infertility.

Ectopic pregnancy is a pregnancy that occurs outside the uterus, unsually in the fallopian tubes rather than the embryo attaching in the uterus where it's supposed to. This causes pain and leads to severe bleeding because the fetus is growing where there isn't enough room to support it. A pregnancy cannot last in this manner.

All of these things are serious, and if you are having a fever it's a warning sign that something is wrong. Go get examined by a doctor, please.