Describing your workflow and how you are using things, from the start to where you are first seeing the noise, would really help people assist you in narrowing down what the cause is.
Things like:
- What camera/lens are you using?
- How are you judging your exposure?
- How are you developing and inspecting your film?
- Where do you first notice the noise as a problem?
Signal noise in visual information (of which photographs are a storage medium of, therefore describing it as noise is perfectly fine in my view) can come from a number of sources, so not having a good idea on what exactly you are doing can make it difficult to pin down.
But as said, a very common source for that kind of look in the original post is a poor exposure on film and then compounded during digitization. (Do be aware that digital elements of photography are off topic for this forum, and will attract rude and condescending comments from some members of the site. However you can still get lots of use out of the site for discussions of film/chemistry, general development, and camera gear, even if you're eventually taking the negatives into a hybrid workflow. You'll just have to take the later parts of the discussion to other areas to avoid overly upsetting some of the locals.)