I have I recently been diagnosed with b12 deficiency and have had 4 weekly doses and am due next dose end dec.i am due next week to see if levels have improved. However this week I noticed that I have no strength in my legs. This became very apparent this week whilst at work when I had to run very briefly. Legs felt like jelly for good couple of hours remained sore in thighs for the rest of the day. That night got several bouts of cramping in feet and calf. The same happened the next night. Now my calves hurt to walk but not at rest. Cramping has been more frequent since finishing loading doses. Should i be looking for other causes for this weakness?Any advise welcome.