Intonation

by girl with guitar problems

Hello,

I ordered an acoustic guitar in April of 2020 and it came in really great shape. Plays very well and I haven’t had any problems with it up until last week. I grabbed my guitar, tuned it and there were two problems I noticed. One: the 6th E string and the A string was constantly buzzing when i strummed it even lightly. And the D and G string are sharp when i play chords but sound perfectly tuned on their own. I have yet to come across any problems like these yet so I am unsure what to do and would appreciate any feedback or tips or instructions!
Thanks.