The Rumblies

I have not been feeling well since coming back from the UK.  It has taken me ages to readjust my body clock, and I'm still not sleeping well and waking up way too early.  But worse than that, I have been having some bad stomach troubles since coming back.  I'm not going to go into disgusting details, but suffice to say that it feels like I haven't passed a solid bowel movement for ages, that I'm going through toilet paper like nobody's business, and there have been times where I've had to get outside the office to release copious amounts of gas since it's been building up to potentially uncontrollable levels.  I don't know what's going on - is my diet in the US that much different, and that much unhealthier, than how I was eating in the UK?  Have I ate something that has really disagreed with me, or that had gone off?  I've never had this problem before to this extent.  And it's got worse the last few days - I would take some time off work if I wasn't so busy and had deadlines this week.  That is probably not helping things either.  It's Labor Day this weekend and I'm supposed to be going down to Oregon, but frankly I'm not sure I really feel up to it as things stand.  Which is a shame.