having to pee alot is normal when tripping..but it burning when you pee I dont think is very normal..you could have a mild urinary tract infection that becomes aggrivated by the mescaline..
Peyote in my opinion is good for detoxing the body..and when you take detox medicines anything goin on like an infection is going to become more aggrivated and symptoms will come to the surface..
If mescaline did that to me I wouldnt take it I dont think...maybe talk to a doctor? The internet is NOT a satisfactory place to obtain advise on this stuff..this is your body and health dude..take care of it.
I know what its like to have it burn when you pee becasue I had that from allergies before..the allergies were causing mild prostatitus..lots of people get this its not that uncommon..but it's not something you want to sit on either..
Best of luck.
Long live the unwoke.