u can try GABA(gamma-aminobutyric acid), 5-HTP(5-hydroxytryptophan), D and L-PA(D-Phenylalanine and L-Phenylalanine), Inositol and L-Tyrosine, in addition to the two that's mentioned by Sam. These SUPPLEMENTS aides our body's ability to regulate or enhance serotonin and neurotransmitters dopamine and noradrenaline. Some may be purchased on its own, others are harder to come by and are usually included in vitamin supplements comonly labled as energy booster for dieting or body building. Google for more info.
WARNING: as we all know, depression affects us differently, what works for one person may not work for others(Omega3 and St.John's Wart has very little effect on me). Similarly, being of naturally occuring does not mean it's completely safe, as these are SYNTHESIZED compounds. Some of these supplements are NOT to be taken with SSRI or MAOI, nor should they be used long term. As with other AD's, these supplements may and may not have side effects. Comon side effects are dry mouth, headaches, stomache discomfort, disorientation, etc. Same precaution applies as with all AD's.
Since you work in the hospital perhaps you might use this topic in discussion with health care proffessionals in aiding your depression from grief and loses.
Hope you feel better soon