ache • hurt • pain

- My head hurts. (Not *pains*)
(intransitive use: you feel pain, possibly
from injury)
- I hurt my foot. (Not *ached* *pained*
*hurted*; irregular verb: hurt - hurt - hurt)
(transitive use = injured)
- My head aches. (Not *pains*)
(intransitive; you feel dull, constant pain)
- It pains me to recall my schooldays.
(= makes me feel sad)