I fall in and out of phase of depression which last months at a time. i often feel suicidal, but md is reluctant to medicate, why would this be?

Not sure: You mention an "md" who is "reluctant to medicate" -- but you don't specify his/her specialty. One reason a doctor might be reluctant to medicate could be substance abuse -- where the patient isn't willing to stop using. Doctors may recommend treatment, but patients can refuse. If not seeing a psychiatrist, please do so asap. Psychiatrists have specialized training & may be better able to help.

Go to next ER : It is hard for me to believe that u have suicidal thoughts, depression and u psychiatrist is hesitant to give u medication. If this is true u need to seek treatment at next emergency room...!