I just dont understand WHY!?

My boyfriend of almost three years is recently acting weird. He's being really really really nice. I know thats not a bad thing but things that bothered him last week hes fine with now... Also he's been constantly high which he does when he cant deal with stuff. Lastly last night his phone rang and I handed it to him (we live together) then he declined the phone call when I asked who it was he told me it was his friend A.J (which is normal) except when I went to send a text(mine was dead) his text voicemail (which is on the same page as textin impossible not to see when texting I wasnt snooping) said that it was just his doctor confirming their yearly check up for tomorrow... so what i dont get is whats all this weird behaviour for hes acting overly nice and is lying about weird things... any help would be appreciated ! :D