Can receive iMessages on MacBook pro but cannot send; also files in cloud won't download to view
I recently noticed I cannot send messages through iMessage on my MacBook pro. Messages come in through my phone, watch, and mac, but I cannot respond on my mac. Also, i cannot open documents that are saved on the cloud on my mac, they say they are loading but do not ever load. My cloud tells me to sign in with my password and then it says "an unknown error has occurred". I am afraid to log out because I don't want to lose my data.
MacBook Pro 13", macOS 10.13