Having nausea last 2 weeks i have nerve pain all over my body. random headaches. and feel like there's pressure inside my head. is it a brain tumor?

Not likely: The nerve pain described is very non specific. Headaches can be associated with nausea and a pressure sensation inside your head. This could be a simple variation of your migraines, a viral illness, or even associated with a reaction to stress. A brain tumor will usually give more focal neurological signs and symptoms. However, see a doctor, given the duration of symptoms.

Possible not likely: Brain tumors are particularly uncommon in patients your age. Headache is a common symptom in brain tumor patients but is also seen in many other conditons, more often than with tumors. 'nerve pain' all over your body doesn't sound like a brain tumor symptom. See your doctor for a referral to a neurologist and likely for a head MRI scan to reassure your about this.