Glad you found the forum, and welcome - just sorry for all that you're going through! Your combined symptoms and autoimmune symptoms in general create a bit of a maze, and it does seem to take a good while to come up with concrete answers. The way they come and go is common as well.
I would stick with the advice of your PCP and doctor friend, and persist in getting second opinions. Be sure to get copies of all your lab results for yourself. Things tend to change over time. Getting pictures of your rashes, swelling, etc. is a good thing to do. So often by the time you get into the doc, your visible symptoms have disappeared. It is a crazy journey, as you said.
Don't be afraid to ask questions of your docs, and clarify their observations. So many of us can relate to that feeling of wanting to hide out and hope it goes away - the pain and fatigue make it harder to advocate for yourself. Take a friend or family member with you to your appointments if it helps.
Hang in there - and while this is ongoing, be sure to take good care of yourself, eating well, plenty of rest, lower both physical and emotional stress levels if possible, limit or prevent sun exposure. Good luck and keep us posted!