Hi Queenie3,
I have record of a Pte S K May 2929616 of the Camerons who was a POW and is listed in 1944 & 1945 as being in Stalag 11A. Altengrabow. His POW No is given as 138808.
With the rank of Pte he was probably in a Work Camp attached to 11A; that is if this is your man.