Take a deep breath and try to relax, it is only one way to dx lupus. You can still have it with the biopsy being negitive. My biopsy is positive and my blood work is negitive but I promise you I have lupus.
You are not weak, I am sure this is all be pulling you down and that it is more of the stress release than weakness. I do not know anyone that has lupus that is weak as a matter of fact I believe that these are some of the strongest people on earth. We don't look sick, we have roaming pains, stiff joints, feel sick most of the time, the sun is most of our enemy, sleep is a reward not something we need, and doctors that don't understand what it is like to look good and feel like crap! LOL. We still have lives, children, husbands/wives, grandkids, summer vacations, and we do it all in pain (most of the time not complaining aloud).
I do hope this helps some that you feel better soon.