I'm 26 weeks pregnant with DC2 and am struggling with SPD which came on about 2 months ago. I work in an office and we are pretty short staffed. By early afternoon my back locks up & it's incredibly painful. I have been referred to a Physiotherapist who has just signed me off for a few weeks (didn't know they could do that!) with a view to doing reduced hours when I go back. My boss is great but I could hear in his voice that this is going to cause major problems, and just feel so guilty. Mentally I am able to work, but physically am a bit of a mess. 
Has anyone else had experiences like this and successful returned to work pre baby? And any advice on how to manage works expectations?