The night before I woke up with a fever, a soar throat along with an achey body and massive headache. I woke up fine the next day. What did I have?

A bad night! It could be one of many things. Perhaps the start of an infection that your fabulous immune system effectively dealt with. If flares again, see your doctor!
A viral infection.. You likely had a viral infection, but what exact virus it was will probably never be known.