What does small little bumps all up and down the inside of the fore arm mean?

See your doctor: This kind of thing can be due to many different causes. I'm afraid if you want a diagnosis you will have to see your doctor.

See a Dermatologist: What you describe sounds like a benign but rare skin condition called lichen nitidus. Usually affects children and young adults. Best thing to do is see a dermatologist who can tell you what you have and provide treatment if needed.