New separation anxiety after a move for a senior dog.

Just recently went through a separation so me and my 13 year old dog had to relocate to an apartment. At our old house he always stayed home and really never left and there was no problems leaving him at home, he didn’t care at all.

Now in our new apartment since it’s just us two and I already work 9 hours a day I’ve been taking him with me everywhere I go other than work. For the first week I didn’t leave him at home during the day, I’d take him to my ex to stay during the day and pick him up after work. Now he’s with me full time and he’s struggling when I leave in the AM. I’m wondering if me taking him along with me is doing more harm than good but I don’t want him alone all day and night obviously. Today I left him with treats and a chew that he likes. I also gave him some calming treats. He was laying down fine when I got home yesterday but leaving this morning he was bothered.

Any suggestions on making this easier on both of us? I’m really stressing out over this, there’s people living below us so I can’t be having him barking excessively.

Edit for added details.

I also have been taking him on morning and evening walks, something I really haven’t done much of before because we had a fenced yard. He’s actually doing shockingly good on the walks, he’s not pulling at all and most of the time there’s slack in his leash, something he’s never been great at.