Simvastatin and synthroid

51 year female, History of Hyperthyroid disease (Graves disease) treated with radiation in 1984, now have Hypothyroid taking 100MCG Synthroid. Began 20mg of Simvastatin 4 weeks ago. Developed mild rash, hives off and on but that was normal anyway so I didn't think anything of it. In the 3rd week a Co-worker noticed that I was walking a little stiff and thought my foot problem was back but I mentioned my knees felt strange. Again this is normal with the cold weather here. This week my knees and calves were swollen and I could hardly walk down the stairs. I called Urgent care and they told me to stop taking the Simvastatin. It's been two days and I feel better but I wonder if my joints will ever be the same? Will I walk normal again? What's next if I can't take statin's? Red Rice Yeast has been banned.