When I get headaches/migraines I get a knot at the base of my head at the neck on same side as pain. I can press and eases pain, comes back on release?

Occipital neuralgia? A neurologist can do a thorough exam and may consider a diagnosis of occipital neuralgia which can be diagnosed by a simple injection of lidocaine. If the pain ceases immediately the diagnosis is made. There are medications you can take to prevent the pain which a neurologist can prescribe.
Headache specialist. Many people with migraines get muscular tension in the neck and shoulder when they get migraines, which can feel like a "knot." but sometimes a mass in the neck can press on the nerves over the scalp/head which causes pain. You should see a headache specialist to see what is causing your symptoms.