Thanks for all the responses, he's home now and much happier
Diet, stress, and a infection seemed to be the culprit.
But if I am remembering right the blockage can happen without the infection, he just happened to have one as well.
I am following all the recommendations from his Dr, which is mainly diet, I'm giving him the urinary care dry food and the urinary care wet food. He will not touch wet food. He is 10 years old and stubborn. I'm afraid if I simply give him no choice but wet food he will wither away out of spite.(my goodness if I ever have a kitten she is getting wet food from day one!) I'm going to give just wet food a go one day in few weeks after his meds are done, when all this stress is behind him. Fingers crossed he gives in and eats it!
It is incredibly helpful to hear that those who have had this problem did not have it again!