Definitely, if you are feeling any pain that is actually preventing you from playing properly....Back it down a good ways and take it easy on yourself. The issue there is two fold, first off...You quite obviously do not want to hurt yourself...the "No Pain, No Gain" mantra should only be taken so far.
Secondly...If it's causing your technique to breakdown and get sloppy...at that point, there is really no point in attempting to practice it at that speed for the time being. You'll only be engraining bad and/or sloppy habits by having to compensate for the discomfort.

I can't say for absolutely sure...But 5 minutes sounds much more like a Tension issue, than a Fatigue one....So dropping the tempo down 20, 30 or 40bpm and focusing in on staying relaxed and smooth, will be a much better option for you, than trying to plow through at the upper end of your control range. Think about the long haul/big picture and give yourself a chance to build up your stamina, dexterity and technique. There are going to be some prodigy types out there who really build these skills quickly....but for the overwhelmingly vast majority of us out there...it's going to take time and patience. So pace yourself and back off when signs of pain or tension creep in.

Don