First responds gold?

How good is it for 21.00 dollars? I took one few mins ago and it was neg! I am 15 days late and I spotted on the 1st 2nd and 4th of this month! I dont know what to do! my chest and back hurt off and on for the past few weeks and my temp been this week mon was 98.4, tue-99.2,wed-99.4,thrus-99.3,sat-98.5 and today 99.1 all in the moring. what does this sound like?