I'm sorry that you are feeling so poorly. No fun at all... but I truely doubt that your symptoms are all from celiac disease. The acne, joint pain and swelling,weight gain, and cold intolerance sound a LOT like Hashimoto's or even a different rheumatic disease. I went through something like that after I had been gluten-free for 2 months: my hair was falling out, my joints in my arms hurt to do simple things, I was extra fatigued... it was all around the time I started taking hormones for my hypothyroidism. I think the change in hormones caused a worse Hashi's flare up OR another autoimmune disease was triggered into acting up (I suspect lupus). Because I had already been gluten-free for two months, i didn't think going gluten-free caused my increased symptoms but I can see how it might appear that way.
Stay on the gluten-free diet. there is absolutely nothing in wheat, barley or rye that is crucial to our good health, in fact even for completely healthy people it is best to limit those foods. I can't think of any reason that being without those three foods would cause a health decline. On the other hand, many people discover other health problems once a different health issue (like celiac) is under control. It's almost like the body relaxes a moment and then allows this other problem to express itself.... kind of like how it is so common to get sick when you start a vacation.
I suggest getting your thyroid tested. Request a TSH (should be near a 1), TPO Ab (should be next to nothing), Free T4 and free T3 (should be in the upper 50-75th percent for your lab's normal range). To me it sounds like your thyroid is under attack.
Other things to ask your doctor about might be Raynaud's, lupus and even rheumatoid arthritis. You might want to get your vitamin levels rechecked too since you were so badly malnourished just a couple of months ago.
Best wishes to you. i know it's tough when you get thrown a curve ball just when you think you should have it all figured out. I hope you find answers soon. Feel better.
Actually, in wheat there is magnesium. Grains are actually nutritious. The only bad thing is the gluten usually.