I looked up porphyria and found a Mayo Clinic site that explains this better. It can also be caused by some medications...depending on which two types of porphyria a person has. Thought you might want to see this. It's not all doom and gloom.
http://www.mayoclinic.com/health/porphyria/DS00955
With all the testing they have run, they should get to the bottom of this. It's just a shame that they were so unprofessional and also frightening. They never did answer your questions either!
Here is another thought. Maybe you had an allergic reaction to the sunscreen you were using. Look at this link. It kind of sounds like what you went through, too. Be sure to let us know what you find out, okay? We really do care about you.
http://allergies.about.com/od/contactdermatitis/a/sunscreens.htm
Sherrine