Very good! Yes, exactly! A thought that has occurred to me, as well. Pretty sure that it was an infection...because the tremors subsided when hit with antibiotics. And, there was the swollen testicle with no STDs. (You don't want to know. Hurt so bad I couldn't sleep). Was in the hospital with fever once.Aside from known cross-reactivity seen with other infections (that were apparently ruled out in your case), it seems that any autoimmune disorder can theoretically cause a false-positive ELISA. The list of possible autoimmune disorders with signs and symptoms that overlap with Lyme disease is probably longer than you and I could even imagine, but I also think that's somewhat irrelevant.
Why?
Well, because if you did have some autoimmune disease (other than a post-infectious process) going on, there's a good chance (although not a certainty) that your body would have provided even more clues as time went on. In other words, most autoimmune diseases have a tendency to get worse or at least provide doctors with more clues in the way of signs and symptoms as time goes on. There are exceptions to every rule, but that's generally how it works.
Your health has actually improved -- not declined -- from what I've read in your posts these past two years. It's possible that the tick that bit you was carrying an unusual strain of Lyme disease or another Lyme-like pathogen. My uneducated guess is that you probably had Lyme disease or something so similar that it's almost academic.
So you have an infection...and an infection that causes heart, neurological and arthritic symptoms. All began shortly after the colonoscopy/tick removal.
But thank you for mentioning the fact that I am now fully recovered, also. I agree with your thinking...forgot to mention that. That would seem to discard the autoimmune conditions as a possible explanation. And even the recovery period is more or less consistent. And there were documented instances of what they call the known sequelae of Lyme disease, such as tachycardia, which lasted for years afterward.
I don't even remember, now, how all of this got started...but my point certainly wasn't whether I had Lyme or not...but was intended to illustrate the issue of inter-lab results not being consistent...and why I perceive placing too much reliance on blot results is perhaps problematic.
But a side issue...possible explanation for the negative blots...kind of intriguing...is what IgeneX claims about why their testing is producing better results. That their reagent includes more diverse strains than the B31 used in most labs...the issue of geographic diversification. That regional strains might not react properly with B31. (And the results from IgeneX were NOT classified as being positive by them in my case).
Now, this issue of strain diversification was also discussed by Henry at one point and I recall that he said that he had been concerned about it, that some patients might fall through the cracks, but that he had been reassured by the CDC that such was not the case, that B31 is sufficiently similar to all strains currently to be able to provide accurate results.
My own view of how to look at my case...
...the famous quote from Sherlock Holmes:
S. Holmes: How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?
You damn betcha.The bottom line is that you're feeling better and enjoying life again. That's what really matters.

Kind of windy, here lately...but tomorrow looks promising and I am hoping to hit the bike trails...beautiful color now and weather couldn't be better...could stand it a bit little less windy, though...I sit kinda tall in the saddle...and that's like Marcel Marceau bicycling against the wind.
