What Causes Chilling And Goose Bumps On The Left Arm?

I am a 23 overweight female. Had a total thyroidectomy a few yers ago and parathyroids were damaged and are now non functional. Also, I have pseudotumor cerebri for about 4 years now. It is controlled with diuretics and I take synthroid and calcium. I also take lexapro 19mg and calcitrol. I recently started getting weirs patches of chills with goosebumps mainly on my left arm but also on my legs too. They only last a few seconds and are not related to temperature. I also have muscle twitching in my hands alot.