REVERE – A man was treated for non life-threatening injuries Monday after he was found stabbed multiple times outside Store 24 on Shirley Avenue, police said.Michael Porter, 42, of Gardner, told police he was stabbed a few blocks away and managed to walk to Store 24 where he called police.Store clerk Karim Erramh said Porter “staggered” into his business shortly before 6 p.m. Erramh and his coworker said they didn’t see any blood and had no idea Porter had been stabbed.”He didn’t say anything to us. When the cops came, he told them what was going on,” Erramh said.Erramh said he hadn’t seen the victim previously inside the convenience store.Police said Porter was stabbed multiple times in the leg and was taken to Mass. General Hospital for treatment. Porter allegedly gave inconsistent statements to police about what happened.No suspects were arrested as of press time.