Let us work together to help him - I feel like I am falling apart!

Just a little history…In 2003 I used to be 105lbs and after I had my son,in 2004, I was put on antidepressants for depression and post partum depression. Ever since then, I have been on several different medications. I was gaining weight every year. I reached my highest weight of 177lbs in 12/08!! I went off my meds, cuz I was tired of gaining weight.. I started 30 mg of Cymbalta in May of this year and was feeling better than I have in years.Then the first week of June, I started with a half tab of Phentermine. I was finally losing weight for the 1st time in yrs. I had the usual side effects. (ie: sweating, some irritability, more talkative, in general was very happy) Then 3 weeks ago something changed. I felt like I was having a nervous break down. My happiness went away. I feel very depressed and overwhelmed with everything. Last week I increased my Cymbalta to 60mg. This week I picked up my new ** for Phen. and it is made by a different manufacturer. It is not effective. I am tired, eating more, no energy. I have no idea what is going on. Am I experiencing a major bout of depression? Was the Phentermine acting as a mood enhancer, which no longer has any effect? ( I have lost 17lbs since starting Phentermine) Does anyone have an idea of what might be going on?