The most likely cause of these headaches is over exertion. Heavy lifting for a long period of time causes a lot of strain and tension in the muscles of the neck and spine. This can lead to a tension type headache
. Generally this type of headache will respond to reducing your level of activity somewhat, such as lifting or working for less time.
Another component of this may be dehydration. With heavy work, your body sweats and loses water and essential salts. The results shifts in fluid and salt levels may contribute to headache. You can fight this by carrying a water bottle with you and making sure to stay well hydrated during exertion. Another factor which may contribute to dehydration are caffeine containing beverages, and you may want to stay away from those.
If these simple measures do not help out, you should see your primary care doctor
. This is because, rarely, a headache can be a sign of a serious underlying problem such as a growth in the brain. This is uncommon, but if the headache is worsening, waking you up at night, causing significant nausea or vomiting
, or if you have dizziness or uncoordination, these would be more concerning symptoms.