IMHO, I think that when we are in pain for so long and all of a sudden, for whatever reason, the pain is gone, we are euphoric. It is so energizing and such a good feeling to be out of pain. I hope you enjoyed your pain free day. The down feeling may also be related to having that pain free day. When we get the relieve we want it to last, but when it doesn't we feel kind of down about it.

I hope this continues and over time your injections last longer.