I Am Having A Hard Time Going Pee, But I

I am having a hard time going pee, but I do not necessarily have the urge. I was constipated and now I have diarrhea. 7 days ago I got done with radiation treatment for cancer on my larynx and which was removed during an operation in early march.
I am drinking gator aid and water okay now. Could not drink anything for about 11/2 day I am concerned on how serious this is, or is just more radiation aftereffects.