I'm certainly no expert, but your levels seem very low to me.
Mine was 600 and I now believe this to be low.
My doctor gave me an injection of B12 in his office. That afternoon and the following morning, I had more energy than typical.
However, the following day and even the following week, I was tired again.
I began taking 1000 mcg of b12 tablets. At first it didn't do much. After a week, I started to feel better.
Perhaps it takes time to build up in the system or it dissapates, etc.
ARe you taking tablets between injections?
Can you take something for your stomach?
I take Axid daily.
It's over the counter now (I do have to ask my pharm. for it though).
I haven't had any side effects with this medication.