Rpr reactive then nonreactive then reactive again over the years but fta-abs always negative.felt flu-like-weakness/malaise for yrs now & docs tested everything &all is normal(brain, psychology,rheumatology etc) but no improvement. feel weaker&weaker?

This is called biological false positive. It's very common, occurring in 1-2 percent of the population. In other words, the same as around 3-6 million people in the US. As you seem to know, once in a while BFP is the result of autoimmune or rheumatological problems -- it's good to hear you don't have them. This is not the cause of your weakness and malaise.

Agree with Dr. H. It is not feasible to provide a meaningful opinion without taking additional history, physical examination and may be some tests. It would be prudent to see your doctor and discuss if you may be depressed. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated. Drink more water.