I have had lyme and co's over 22 years so yes it's possible to have it and not know it as your headline asks. Spending on your immune system, it can hide for a while and in times of stress, come out big time.
Another thing to note: the ticks that carry Lyme disease often also carry one or more other bacterial infections as well. A wise and experienced Lyme specialist knows this, but not all docs are as wise and experienced as they like to think they are ... if you get my drift.
Based on your symptoms and history, a good Lyme doc will be able to tease out the (often subtle) symptoms to clue the doc what other infections the tick may have gifted you. These additional infections (called 'co-infections' as a group) often need different medication/treatment from Lyme.
Best wishes, and let us know ho you do --
Absolutely yes, you could have carried a mostly dormant infection for many years, and it's possible for it to finally become active if/when your immune system is under stress. And then, boom. The difficulty now is that the spirochetes are probably well entrenched behind the protective barriers they create (biofilm), so if the test they choose is looking for antibodies, it may not detect any because over time the immune system comes off high alert because it can't find the Lyme bacteria anymore, and the antibody count comes way down. You really need a Lyme literate doctor to look at the details of the test results PLUS consider your symptoms and the opportunity for a tick to have gotten to you (that's a yes since you actually remember it!) and then see if a treatment plan for Lyme is justified/recommended. It's critical to find a dr who is informed about Lyme, and even better if they really understand it.
I have just finished 4 months of antibiotics and am starting on an herbal regimen now (dr wants to mix it up) and I can tell from the herxing that both treatments have been and are now upsetting the little buggers (good!). I had similar symptoms to yours (yes, and more also!) and other things I never connected to "something's wrong" and just thought aging or old injuries or simply that's weird!
From your symptoms Lyme sure sounds like a good candidate - I hope you are able to find a good LLMD and start getting well again.
Many of us never see the tick or get a rash, so it's entirely possible to have Lyme without tick or rash seen. It is good that you are going to see the doc, but be aware that there is a huge split in the medical community about Lyme: regular docs don't understand Lyme and don't know how to test, diagnose or treat it properly. Your own doc may mean well, but may not have the experience or knowledge about Lyme that is necessary. This is nothing against your doc, but simple fact that so-called 'mainstream medicine' really does not understand how to diagnose or treat Lyme and other infections carried by the 'Lyme' ticks. Lyme can stay with you indefinitely until appropriate treatment is given ... so-called mainstream MDs don't understand this, and it is critically important to find an MD who understands Lyme as viewed by ILADS, which is a voluntary group for MDs: International Lyme and Associated Diseases Society. Not all ILADS member docs are geniuses, so beware, but it's a good place to start. This new page format doesn't say where you are located, but that critically important to getting diagnosed and treated. You are not grasping: you are being wise and aware. ... Note that the tests your current doc like uses (ELISA and Western blot) may well not be accurate, esp. when you have been ill so long. That's why seeing an ILADS doc is so important: ILADS docs use different test approaches that are more accurate, esp. in patients who like you have been ill for so long. You are not grasping at straws ... you are strong and wise enough to keep battling the Lyme bugs. If you go to the ILADS website, there is a referral function to help you find an ILADS-member doc near you. Not all ILADS member docs are geniuses, but you gotta start somewhere. If you can find a group near you for Lyme patients, they may be good sources of a nearby doc who really DOES understand Lyme and how to kick it. Best wishes to you -- let us know how you do. Now go for it!