German Shepherd with OCD? Anxiety?

Our 1 1/2 year old German shepherd seems to have some serious mental health issues and he's been reallly difficult to have in the house. We love him and he's very sweet, but I don't know how to help him. We think he has OCD which is common for German Shepherds. Whenever he's around people, usually it's just myself and/or my husband, he acts crazy. He chases his tail nonstop slamming into everything and everyone who gets in his way. He sucks the skin on his belly until it's gray and raw. It's like living with a wet tornado all the time. The thing is, it's only when he's around people. If we go upstairs, he lays down and goes to sleep. He's never been abused and doesn't seem to be afraid of people. He definitely prefers company. If there are people around, he chooses to be near them, but acts all crazy. We've talked to the vet and tried a few different medications. None of them have had any effect. I feel bad. It doesn't seem like a very good way for him to live. And he's driving us nuts. We would never give him up. We're definitely committed to taking care of him, but I feel like we're failing. Does anyone have any ideas?