new mattress is hurting my back, could this be a transition period?

I had a somewhat firm twin mattress and a week ago I upgraded to a full serta perfect sleeper pillow top and a 2inch memory foam pad i bought from someone for only 300.

I’ve been waking up with neck aches, and some upper back pain, which is wierd because usually i experience lower back pain. Memory foam is supposed to help my spine align correctly, so im wondering if the pain is a result of a transition period?

pain aside, i seem to be sleeping better, and i’ve been able to remember having dreams which is a first!

Thanks for the help, i’m hoping this is a transitional pain?