YOU SAID:

My head has a lot of pain right now because I hit it while playing football in my room with my second cousin

INTO JAPANESE

部屋で二人目のいとことサッカーをしているときに頭を打ったので、今は頭が痛いです。

BACK INTO ENGLISH

I hit my head while playing soccer with my second cousin in the room, so now I have a headache.

INTO JAPANESE

部屋で従兄弟とサッカーをしているときに頭を打ったので、今は頭痛がします。

BACK INTO ENGLISH

I hit my head while playing soccer with my cousin in the room, so now I have a headache.

INTO JAPANESE

部屋でいとことサッカーをしながら頭を打ったので、今は頭痛がします。

BACK INTO ENGLISH

I hit my head while playing soccer with my cousin in the room, so now I have a headache.