Gosh, sorry - I forgot to update!
All's well that ends. The dip stick thing I bought for blood sugar at Boots had Rupert's blood as 30+ and his tum was solid like a drum so big panic and off to the vets. The 20 min drive must have shaken something lose because by the time I got there his tum was fairly soft, his bloods were 12 and the vet could hear some gurgling but not much. A few days of metacam and metoclopramide and Rupert seems back to normal - he's out munching grass. Can't stand the stress - I really thought he was a goner. Thank you a lot for your help Mighty Max.