Hi Geri,
I haven't read all the responses, so don't know if anyone else has said the same things, apologies if so. You said you had a hypo, went high after, then corrected with insulin. You're not meant to do that, as a) your body needs that glucose to 'restock' the liver to help pull you out of your next hypo, so all that sugar goes somewhere useful but having extra insulin stops that from happening and b) once you've had one hypo you're more prone to another, so you're supposed to leave resultant high sugars alone for both those reasons. I've seen it referred to by HCPs as the 'insulin rollercoaster' and lots of people do it without realising what they're doing 'wrong'. So, hard though it is, you try to not overtreat the hypo and if you go high - leave it. If you wait and see, it will most likely go down to a much more reasonable level a few hours later, I tried it myself and that's exactly what happens. I hope this information helps clarify some of what might be going on with your ups and downs.
There are many medical conditions other than diabetes and thyroid that could be causing your symptoms so I would suggest you might want to discuss this with your doctor again. I have chronic fatigue syndrome, for example. If you really feel inside yourself that there's something else going on, don't be fobbed off, keep going back until someone takes you seriously. I've just been fobbed off for two months being told there's nothing wrong with me when actually I've had a serious health problem that could have turned extremely ugly and I'm now on three different types of antibiotics - only because I finally insisted on retesting everything.
Good luck, I really hope you feel better soon.