Since starting Singulair for hayfever, I have had pins-and-needles feelings in arms and legs. Also horrible pain in the right arm keeping me awake even after taking a double dose of Ibuprofen. The right arm has previous RMS injury. Then the pain started in my legs, above the back of the knees. I have to keep moving to keep the pain away. Still all pins and needles in both arms and legs. No more Singulair for me.