big leaf phal yellowing leaves and looses buds, help

[behtash]

hi

recently i got a big leaf phal as a birthday present (last week) at first i noticed it had 2 down leaves yellow with some black small spots and i thought its normal for them to get yellow and fall, but 2 days ago i saw the leaves are yellowing with black spots (5 out of 8 )
i have several orchids and i put the environment in a good temp / humidity / light and have several other orchids but never saw such thing
it also looses buds, at first all of the fresh and stiff! now i see some of them are getting red and falling down afterward, i upload some pics of the plant

can anyone help me as i care for this plant and the person who gave it to me