Hi Wiseguy,
You clearly have something neurological going on, given the symptoms you mentioned. I agree with Lymester, Lyme is certainly worth pursuing, especially if you remember having ticks on you as a child. That is key, with or without the rash.
I was bitten at age 14, and like you, there were no immediate symptoms--my body deteriorated gradually over the past 16 years. I went from doctor to doctor searching for answers, and wasn't tested for Lyme until age 29. Then I learned I have Lyme, Babesiosis, and Mycoplasmas. (I also have Hashimoto's, Adrenal fatigue, weak bones, asthma, extreme food and chemical sensitivites--esp. to molds, formaldehyde, and chemicals, a bunch of heart symptoms, low platelets, urinary urgency, candida, leaky gut, and some damage to almost every organ in my body--too much to list).
Lyme produces neurotoxins as a waste product, but your symptoms sound pretty severe, so I would guess there may be something more going on besides Lyme.
Neurotoxins can come from molds, pesticides, pfiesteria (in areas of Maryland & Delaware), and based on your mention of depression in your family (even if not in you), your mention of possible MS/lesion, and your history of smoking, I would think mercury or other heavy metals may be involved. A hair test can check for heavy metals. I had a lot of mercury, and felt a substantial improvement in my mood after I got my amalgam fillings removed and detoxed with the supervision of my MD. My plantar fasciitis, foot pain, and TMJ pain went away after this detox. Detoxing from mercury should be supervised, however, because it can do damage if not done correctly. A general rule of thumb is to start weak and slowly move to stronger detoxing, monitoring your response. The Autistic community is up on this sort of information.
Food additives that can contribute to neurological symptoms include artificial sweeteners, artificial dyes, and flavor enhancers. Flavor enhancers go by 30 different names, the most common of which is MSG. (See the documentary: Sweet Remedy, and the Russell Blaylock's book, Excitotoxins, the Taste That Kills). I get headaches if I eat these in large enough quantities.
Foods that can contribute to neurological symptoms include nightshades. Nightshades include white potatoes, tomatoes, all peppers (except black peppers), and eggplant. These foods contain solanine, which is a natural pesticide for the plant, but it accummulates in the body creating neuroinflammation. I get burning eyes and joint pain when I eat nightshades.
I hope you're able to reverse some of your symptoms! I know how frustrating it can be to be told to just "accept" your physical decline. Keep searching, and eventually you will find answers. They're out there--you just have to dig!