first of all i need to know what was the drug how long you took that medicine and have you felt tolerance to either effect or side effect of that drug? at this stage i like to inform you that with current available medication only two thirds of the patients improve the remaining and the other one third fail to improve even after trial of multiple drugs. the next course of action is decided on the basis of residual symptoms magnitude of improvement comorbid medical and psychiatric conditions tolerability and affordability to name a few. in your case your doctor may be right but if you are taking same medication for more than six weeks then it is time to intervene. if the concentration problem arose after the use of drug then it might be the side effect of drug itself and in that case it needs replacement. if the prescribed drug dose is in lower range side then increasing the drug dose might be the solution. at this stage i would like to tell you that drugs available currentlyt may be used for improving concentration after a detailed history of the patient and review of all previous drugs. i suggest you to approach a psychiatrist either online or in person for correction of your problem. you can also book a slot for an online video chat session i will be happy to help you out.
i am a depression patient and taking medicines for long time. now i feel very sleepy and facing concentration problem.