The middle of my chest hurts. when i touch my breastbone it hurts a bit. the chest pain reduces when am resting but increases during physical activities especially when am carrying bucket of water. i also feel headache and muscle pain, heartburn?

I assume there hasn't been a recent injury or overuse syndrome from exercises or certain chores. A key diagnostic sign would be definite tenderness at the junction of the rib&breastbone. This would point to costochondritis, inflammation of that joint. Resting,applying cold alternating with hot applications & taking advil or aleve,if you can, should improve the inflammation. See your MD as needed.

It is not feasible to provide a meaningful opinion without additional history, physical examination and may be some tests. It would be prudent to see a doctor. Wish you good health!