"Same brand" different mg/ Less effective?

[Klaire]

Hi all,
My first few scrips of methylin (Mallinckrodt) were filled with 5mg tablets at the Kaiser pharmacy. She was having me start with 5mg caps to figure out the correct dosing for me. I ended up not taking as high of a dose as but more often. So in the am 15mg, three hours later 10mg, three hours later 10mg etc.

This time she asked if I wanted to try Concerta (not ready to change yet) or she was going to up the mg on the next script so that I didn't have to take so many pills in a day.

So I got the refill at Kaiser and it was in a prescription bottle (the others were sealed from the manufacturer in 100 pill per bottle dosing). The new script was in a Kaiser pill bottle and inside were larger white pills that were supposed to be 10mg.
So I am taking the same mg per dose but today they have less effect on my focus. I feel jittery (not speedy), but a bit shaky and do not have as much focus as the lower mg pills even though I am taking the same dosage.
They are supposedly the same brand (it has a white larger round pill with a M on one side and a 10 on the other. Do you think it might be made by someone else? I don't have the original bottle with label because they filled in a Kaiser bottle?
I am just a little confused as to why it isn't working the same? Anyone?

P.S. (Mods) Not sure if I am writing this in the right place, feel free to move it if need be.