Implantation bleeding?

Af last visited May 9th and my cycles are usually 33 days long there was one time when it was 44 days. Last Friday I started spotting it was pink then got darker like a brown. It was like that for a while but only occasionally when I wiped. I'm terrified of taking a pregnancy test since it's always negative or af shows up after I spend the money. This time seems different my boobs have been hurting and I have been tired more emotional than usual and I have had a slight fever of 99.7 then 99.1 yesterday. Could that have been my period just very light or should I buy a test just to be sure?