Woke up today with a stiff neck from below ear downwards, feel unwell and lump on sternocleidomastoid muscle. my neck really tender hurts to touch?

Get checked out: A lump on your sternocleidomastoid could be a lymph node. In that case, you might have an infection or inflammation. There are many causes of stiff neck, but in the setting of swollen lymph nodes, i would be sure to be checked out. Meningitis can cause stiff neck, for example, and you don't want to miss that diagnosis. I would see a doc asap.