Seeking advice to help my dog

Hey guys, I’m posting this here because I didn’t know where else to post - but I need advice. So for the past 2 days, my dog has been having problems with his teeth. I checked his teeth yesterday and he has red, swollen gums and tartar built up on his big molars. The rest of his teeth don’t have that build up but the gums are red and swollen. He isn’t eating a lot and won’t touch his solid dog food unless I hand feed him but even then he doesn’t want to keep eating after a little while. I softened his food up and he ate more than he has been but still didn’t finish it. He isn’t whining or anything and he even let me open his mouth to look at his teeth. I’ve been freaking out and feeling so guilty that it makes me sick to my stomach. I’ve already cried. He just turned 6!!! He’s still a baby :( My question is: do I take him to a vet or straight to a veterinary dentistry place?

*pic of my dog