YOU SAID:

i've been watching you for several days

INTO JAPANESE

私はあなたを数日間見てきました

BACK INTO ENGLISH

I've seen you for a few days

INTO JAPANESE

数日間あなたに会った

BACK INTO ENGLISH

I met you for a few days

INTO JAPANESE

数日会った

BACK INTO ENGLISH

Met several days

INTO JAPANESE

数日会った

BACK INTO ENGLISH

Met several days