He started the B12 around October after the first suspected spinal stroke was diagnosed. We have been using 'Doctors Best' brand 1,500mcg BID until 1/6 when we doubled it to 3,000 mcg BID. Mum has just received the Zobaline so we will swap to that and give him their standard one 3,000 tab once a day dose. That bottle will last two months at that dose, if we don't see improvment by then we will give up on he B12 for him and accept that it is how it is.