Is it notmal to always feel stiff and creaky after you start getting fit?

This is not necessarily a fitness question persay, but i figured this would be the community to ask. About 3 months ago i started a new job, a factory job, where i'm constantly pushing and lifting tonnes of weight daily. i've gotten used to it, i don't feel nearly as sore as i did when i started, the only thing is how i feel when i wake up.

you see, when i first wake up the first thing i notice is how stiff i am, literally it feels as though each of my individual muscles has turned into cold rubber. And the cracks! every time i move now something or another pops or cracks in any given part of my body. Suffice to say none of this is painful, just... uncomfortable. It's not like they gave me a "how to adapt your body to suddenly doing manual labor 101" pamphlet when i joined, so what exactly should i be doing different? Or is this just a normal phenomenom that i'm not used to?