Muscle fatigue...leading to nausea?

Hey guys;

Lately, when I work out small muscle groups in my shoulders, I get this overwhelming fatigue not only in those specific muscles, but also in my entire body, with some mild short-lasting nausea. I was wondering if this is something common all you bros encounter or is something wrong. I may have a mild cold, but feel good. When I workout my pecs,bis,tris it feels good; you know the pumped up feeling after working out. One last question, is lactic acid build-up in muscle tissue counterproductive to size and strength or is there no connection?

Thanks

Hmmm.... the only time I get this is when I workout large muscle groups (such as quads/glutes). Leg day, if I've really busted my ass, I almost ALWAYS am ready to throw up on my walk back to my car. I used to think I was not eating enough/drinking enough prior/during workouts - but this is not the case...atleast for me. I believe it's a combo of lactic acid buildup coupled with oxygen being sucked up by the muscle.

However, I've never had such an experience working out something as small as my shoulders....