Hello, Daniel. Thank you for doing your homework. You are improving now. Keep it up! See you on Wednesday! :)

1. sick : I was sick with a cold last week.
CORRECT: I was sick last week. I had a cold.

2. stomachache : I have a stomachache yesterday.
CORRECT: I had a stomachache yesterday.

3. birthday : My birthday is October 9.
CORRECT: My birthday is on October 9.