Timing getting WORST!!!

My goodness , yesterday's main set we did 5 sets of 100m sprint and it must be 4 secs off our PB. Guess what i did?? my PB is like 56.67 secs so i suppose to do bout 1:00 or 1:01 . my first 100m was 1:01.92 , not bad la...hahaha but second one 1:04.22 then the third one 1:05.72 then fourth one is 1:09.60 then the last one i did 1:11:02.....OMG!!!!! my timing is getting worst...i suppose to maintain at least around 1:04....WTH...!!! sigh...old already...it's a sign tht i should stop swimming...hahaha... but i wanna enjoy training b4 i totally stop... =) anyway tht's all
ARGH!! my legs are aching!!!

*later