About ten days ago I capsized from a kayak in very rural France and bumped my head on a rock (stupidly I didn't realise how fast flowing the river was and no one was given helmets). I felt a little light headed afterwards for around 20 minutes but no headache, nausea etc. I applied a bag of frozen veg and rested! I had a bump which went after a few days but it still feels tender to the touch and very occasionally stings slightly to the touch. Is this normal?