Suggest Treatment For Stiffness In The Muscles

Hello I have been taking 40mg of omneprozale, and 150mg of ranitdine and switched to these on Monday after going to the DR. because the 20mg of omneprozale I had been prescribed a month or so earlier was not helping, I have also been feeling kind of out of it and weak, sometimes muscles feel kind of stiff, and I have had pain in my right leg for a couple months but these were not really checked and now for the last couple of days my stool has been black is this a cause for concern?