u/BetterInsipiration

Is there any phenomena which explains this- where a person who has only taken methylphenidate as prescribed (20mg IR twice a day and 10mg IR in evening) lost all its focus enhancing and therapeutic effects after it working properly for 8-9 months. The only thing I feel is euphoria now but no therapeutic effect. So I took 2 months complete drug holiday and then restarted but it had no effect. Anyone here that went through similar situation?