Hi there and welcome! I had JRA as a child. In my late teens they said I outgrew it. However, around 20 I started having some problems with my knees again....still they claimed I did not have RA....when I was 25 my feet suddenly got really bad and they shrugged their shoulders saying my blood work looked fine - it must be in my head.....after a while of not figuring out what was wrong (I was unable to walk for years) with me, they said, "oh, you must just have RA now.....it can happen" However, none of the traditional NSAIDs would help me whatsoever and x-rays were not showing any signs of a severe problem. So, there was not much anyone was doing to help me.
It wasn't until after I had kids and was in my early 30's that the X-rays confirmed the arthritis, a few years of severe psoriatic arthritis symptoms that the doc at the time actually witnessed do they say, 'you have it for sure!' and yet, my blood work is still often 'normal.' But, bless the doctor who sat me down and said, "let me tell you about YOUR life...." and he began to explain it to a T (w/o my giving him this knowledge) and finally validated that I wasn't crazy!
Dont' quote me, but I think a Lyme's test is pretty black and white, unlike the RA test. You either have it (lymes) in your blood or you don't. Do your feet turn bright purple then white? Ask about Raynaud's Syndrome. When you have them check you for Hypothyroidism (per Mary's suggestion), also see if they can check you for Hashimoto's as well (sp?) - it sounds like you may need to have a full blood panel done to rule out a variety of problems that may be causing this. Fatigue and brain fog can also be caused by a poor functioning liver as well as many of these diseases. B vitamins, rest, water, and folic acid can all help with it somewhat.
Good luck. Keep us informed on your progress and findings. ***