I switched from regular cymbalta to duloxetine and even though only difference is inactive ingredients, i'm having issues.. different?

Possible.: Let your doctor know about these changes, he can prescribe brand only. Insurance might make you pay a little more for brand, depending on your benefits. .Generics are just tested for bioequivalence, not efficacy. Efficacy and safety, can be expected to be essentially the same, but this is an assumption, not a fact.

Maybe...: I haven't run into this with duloxetine, but with some other meds. The generics are supposed to be the same but are generally manufactured by other (not the brand name) companies. They may actually not be the same. Ask you pharmacist for the name of the manufacturer of the generic and ask him/her to order you generic from a different company.