We're told doctors performed a bunch of tests and say the episode over the weekend that landed Dog in the hospital appears to be stress and blood pressure-related. But, thankfully, we're told doctors are confident it was not a full-blown heart attack.

What's more ... doctors performed an angiogram and it was normal.

Dog's family is worried about him. They say he has had trouble handling the stress associated with Beth's death, a subsequent burglary and various other issues. It's all been exacerbated by high blood pressure, and the chest pains he experienced over the weekend were scary and a cumulative effect of all these events.

The good news ... one source said Dog was released from the hospital late Monday night, and is now resting at home.