I'm almost 23, female, and on Synthroid Levothyroxine 50 MCG for my thyroid (I take 25 MCG one day, 50 MCG the next day, 25 the day after that, then 50, etcetera). I take a multivitamin and Tums for calcium daily, and Zyrtec as needed because I have idiopathic hives. My weight has been stable between 150-155 pounds (I have a large frame according to the wrap-your-fingers-around-your-wrist-test). About five days ago, after I got out of the shower (at night), I noticed the tip of my right big toe was tingly and numb (sort of like it is when it's asleep). I shook it around a bit and massaged it, but it's five days later and there's no change. It doesn't hurt and is still pink, so I don't think it's a circulation issue. I also recalled that I sometimes wake up with fingers or wrists or hands. I have also recently started to have lower back pain, as I am a college student and have a rather heavy schedule requiring me to tote books all day long. I just want to have an idea of what's wrong, whether it's something serious, and whether I can do anything to prevent it from becoming something serious... Thank you for your time.