This is somewhat similar to the path I took relative to ME/CFS and Lyme. I am oversimplifying a bit for the sake of narrative, but I got a bull's-eye rash. I knew what it was immediately. I had never had Lyme at the point, but I felt I could ride it out and let it resolve on its own, especially since I was a partner in a research firm, and I was reluctant to take any days off unless I had to. Sure enough, the rash subsided without me going to the doctor's. About a year or so later, I started having trouble with my balance. I had trouble with driving a car. I had depth perception issues. I wrote a lot, and I started having disconcerting issues there. I didn't know it, but I believe this was the beginning of my struggle with neurologic Lyme. Like you, I did not have swollen knees. A year after that I got shingles, and a nasty virus, and one year later I got another bulls-eye. This time the tick was embedded and the doctor removed it himself, and after a few days feeling like I had a bad flu, I was diagnosed with Lyme. The way you describe your muscle and joint pain and of course PEM, suggest ME/CFS to me as well (not trying to diagnose you, of course), but if it were me, I'd want to do a western blot - if only because you might have had the EM. But it's not inexpensive, and I do not know what it would show, and you'd likely have to buck the system because in the UK the test usually administered is the C6, which is an ELISA. In the States, in endemic areas, people try to find doctors who know a thing or two about Lyme, they take ten days or so of antibiotics right up to the day they get tested. This, in theory, agitates the spirochetes in infected patients. This triggers an immune response, and you see more positives on your tests - but only if you're, in fact, infected. It's a process, it's not cheap, and testing sucks, so I wouldn't second guess you for a second if you just sat pat.