Re: costo or ???????
I don't know if this will help at all.. but I know that when I get stressed even if it is a minor amount of stress my chest gets tight which then makes my chest hurt. My costo is really bad when I do repetitive motions and can be aggravated by sitting in positions that cause the chest wall to tighten instead of being able to relax. Maybe the way you are sat in your new job is making your chest hurt or like myself just a little of bit of stress can help to make it worse.
I don't want to say that is the reason why your chest is hurting but maybe you should go to the doctors just to double check that everything is fine. As until you know for definite that everything is ok you won't be able to relax.