hello! thanks in advance for any thoughts on this

We have an 8 year old lab/collie mix. He's a great dog, very easy, no fusses.

For a few months now, about once a week or so, he will get up in the middle of the night, walk to one side of the room, stand there, walk back to the other side of the room, stand there.....pacing, but not constantly. He'll just stand around, acting uneasy.

Another thing he does is while laying down peacefully, he'll suddenly jump up as if he got scared of something, put his ears back and walk away from where he was laying. He'll also walk out of the room and look back in the room as if there's something there.

Over the last few days, my girlfriend (his life long owner) has been away and he won't eat his food. He'll taste it, but eat very little. He usually has a voracious appetite. I don't know if his not eating is related to the earlier odd behavior, or just him being anxious that his "mom" is gone. His odd behavior has been far worse over the last couple of days though.

Thanks for any advice you can offer!