What Causes Forearm Muscle Aching, Discomfort And Stiffness After Tattooing?

I had a tatoo done on my forearm three weeks ago and it has healed nicely, no sign of infection (no redness, spots/rash, pus or swelling and not sore to touch) however im feeling some discomfort and aching in the muscle directly beneath the tattoo that has only been present for the last few days, it feels almost like the stiffness you feel from having your blood taken. I have had tattoos before but never experience this with any of them, do you have any ideas?