Constant body and leg aches

22-23 weeks and still working. On a rotation WFH & WIO. Started going back to the office after few weeks of work from home during the 1st trimester and a half. Never thought the aching will be more severe and from sitting on the chair for too long. Any mummies experience the same issue and how to deal with it? :( would want to let my manager know about it, but afraid they might not understand or seeing as an excuse for wanting more WFH.