Suggest Treatment For Pain In Head After A Head Injury

i have a terrible headache following a fall (and head injury)
41 years old, 95 kgs. fit medically
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I fell yesterday in a changing room and injured my head. When i went down, i felt my whole body get into a shiver (kind of a shock or something like an electric strike). I was down for only a minute or less. I felt too much pain and took a pain killer. Afterwards, i was able to get back swim but felt too much pain on the injured area when the head touched water. However after some time, the swimming was fun and the pain was far from me. Later after changing to go home, i felt very tired and like i had a heavy head. In the night i took a different pain killer and slept soundly. During the day, i have been feeling pain (in the head) almost like headache or more and also i have been feeling like am not 'in my body' - know what i mean? [like am just floating]