Dr. Conrad Murray's CRYING VOICEMAIL -- I'm in Constant Pain

Jail has broken Dr. Conrad Murray ... physically and mentally ... this according to The Doc himself, who's been calling everyone he knows HYSTERICALLY CRYING and complaining that he's in "constant pain."TMZ has obtained one of the voicemails Murray…

Dominique Swain Donna Feldman Drea de Matteo Drew Barrymore