You may speak to your employer only if this is impacting your work significantly. Otherwise, you may mention that you're dealing w/ health related issues w/o necessarily having to go into great detail.
If your work offers EAP (employee) assisted benefits, you could receive some free counseling sessions. In VT, you could also check about receiving services through the local community mental health center. These centers are usually available for individuals w/ financial concerns and/or w/o insurance. Listed here -http://mentalhealth.vermont.gov/DAlist
Being on SSRI medication for a long time, can cause refractory depression. After a while, your dopamine level (besides serotonin) can be affected. Some psychiatrists prescribe Wellbutrin or other dopamine agonists.
You could share what you're comfortable with. There is no requirement that you should go into great detail. It is understandable that individuals get ill and need to take care of their needs whether of physical or psychological nature.