Getting treated different in the workplace

I just went back to work this week and it's mostly men, I feel like the guy who was covering my position for me (a tank they want to hire now) has a more valued opinion in the office than I do. I feel like I'm being treated different already. They are hardly giving me any of my work back and when we have meeting my opinions are overlooked and the new guys are taken into consideration and applied. I've been there 3 years and ran the department myself was always told when we hire newbies i would move up since I started the design department. Now I'm told I'm an equal with this new guy and he's kind of been bulldozing me a bit with his opinions and it's making me so self conscious. Is going back to work this hard on everyone? Has anyone else felt treated differently? My boss also made a comment about keeping him "in case I leave" idk maybe I'm just sensitive because I just came back ugh