Lyme disease is an infection spread by the bite of certain types of ticks. If caught and treated early, the infection most often clears quickly. If not found until the later stages of infection, people with Lyme disease are more likely to still have symptoms (what you feel) after treatment. These include fatigue (feeling very tired), poor sleep, and muscle and joint pain.
Lyme disease results from the spread of Borrelia burgdorferi bacteria living inside infected ticks. These small ticks can attach to human skin and go unnoticed, feeding for a few days. During that time, the bacteria pass from the tick into the person, before the tick dislodges. Other infections spread by ticks may occur at the same time (co-infection) or separate from Lyme disease. These also require prompt medical care.