Felt cold yesterday, struggled to get warm, heavy legs and arms. now very painful low back pain on left and right, what could it be?

Many things.: You may have a viral infection which should subside in about 10 days or possibly a kidney infection. See a doctor if not resolved in a few days or getting worse at any time.

Possible virus: These symptoms are consistent with the early stages of a flu like viral infection of the respiratory tract or intestines. If symptoms of a head cold, cough or diarrhea do not develop and fever and chills persist, see your physician as a more serious infection may be present. If urinary symptoms appear a urinary infection may be present.

It could be : From a viral infection, muscle strain, arthritis, pinched nerve etc. See ur dr for reassurance. Take care!