Do you guys have experience in giving out alternative medicine for treatment resistant depression such as modvigil or memantine or something else?

Depends: You need to be sure you have the right diagnosis first. Once you are sure you're treating depression, either unipolar or bipolar, you might consider speaking to your doctor about lamotrigine. This traditionally "neurologic" medicine was proven to prevent the depressive episodes in bipolar disease, without exacerbating the manic episodes. Worth a try at a small dose if you're out of options.

Yes: Yes--so-called "off-label" uses for these meds are sometimes helpful.