Headaches on the back of head (occipital region) are usually due to stress, injury related to muscle tightness or pinching of nerves
You can start with a pain killer like naproxen 500mg twice daily for 2-3 days and observe for improvement in symptoms
Meanwhile avoid lifting weights and minimise stress.
Next Steps
You can opt for my consultation after this period as proper evaluation is required to recommend further treatment
Health Tips
do not take painkillers more than necessary as it leads to stomach disturbances