What Causes Burning Sensation In Feet While Being On Copaxone?

Hi ! I have been using Copaxone for the last 5 years (1 injection daily 20 mg). About 7 months ago I switched to the 40 mg. so i would have to give an injection only 3 times a week. It s been great and I ve had no relapse or symptoms in 6 years. On Monday I missed the injection because I ran out the door for work so I didn t give myself another shot until Wednesday morning. I have had burning in my feet for the past 2 days. I know it is a symptom of MS and am wondering if it could be because I missed the injection on Monday (which would mean my last injection was the Friday before so I didn t have any injections for Saturday, Sunday, Monday and Tuesday)?