Hello, I am sorry your son is having such a painful time. I have PKD and was transplanted 5 years ago. I had cysts burst, which were painful, but your son's situation does not sound like that to me. I do not have medical background but the symptoms you are describing sound more acute.

Have you tried the PKDcure.org site? They have a lot of resources, including clinics of excellence for PKD care. I looked up clinics specializing in PKD in Colorado and found these two clinics: University of Colorado Anshutz Medical Campus in Aurora (303)724-7797 and Colorado Kidney Care in Lone Tree ( 303) 799-8760.
https://pkdcure.org/coe-search-results/?search=colorado
PKD can cause anurisms, so when I suffered from headaches at one point, my doctor did brain scans to insure I did not have an aneurism. I did not, but it is a very real side-effect of PKD and should be checked out if your son is having headaches.

My only other piece of advice is, continue putting your son in front of different doctors until they figure out what is wrong. There were times I was VERY difficult, and left one doctor to go to another in a different group or a different hospital. That self-advocacy is why I am alive today.

I am sending you love and strength.