hi..it may be early onset dementia or depressive symptoms although it will be counted upon how you feel these days..sad or normal..I don't know why you are taking lithium..may you have bipolar disorder
or it may an add-on for duloxetine to treat resistant depression..so please consult your psychiatrist
and a detailed mental status examination
should be conducted..also a brain-imaging should be done..diclofenac
is nothing to do with forgetting..have a good health after a proper consultation..