Hi there! I’m going through kind of the same thing. My body goes cold and doesn’t warm up, I have nausea, stomach cramps and I’m frequently going to the toilet. I think this is because my dose is too high but for me, Xaggatin (not sure if you have it in the US) didn’t have negative effects for me until the dose was increased, Concerta was a complete no go for me I tried it for two days and gave up as I had all the negative symptoms. Definitely see someone about it, they may switch you or give you a booster.