Hi needs help,
I had this problem too, but it only started after I started treatment. The muscle weakness/tiredness was worse than the pain, but I also had leg pain. My Dr thinks it might be related to my adrenals. When you're sick, your adrenals are under a lot of stress. Many people with Lyme disease have adrenal deficiencies. These can get worse or happen at any point before or after treatment, as your adrenal system is still under stress after you are on treatment. Supplements designed for people with CFIDS or Chronic Fatigues system could help- I am on things for both. Also, antioxidants can help.
Sorry- I'd love to give more of an explanation, or more info, but I'm pretty brain-dead today,, so I'll stop before I stop making sense.