I would say that if it's more of an extreme issue, that you should get your adrenals checked with a 4 collection time saliva test. This site has some good options and a link to order your own saliva testing if you can't get your doctor to order it for you:
www.stopthethyroidmadness.com/adrenal-info/ But other than that, Lyme symptoms are very well known to cause that roller coaster of symptom severity. It's actually one of the hallmarks of Lyme.