What can I do to please Allah the Almighty, as I have begun to fall short in performing the supererogatory acts of worship (Sunan) and night vigil (Qiyam al-Layl) due to a constant headache?

Regarding pain, consult trustworthy doctors, in accordance with the Prophet’s (peace be upon him) recommendation to seek treatment. To earn Allah's pleasure and love, first fulfill the obligatory duties, then increase your voluntary acts such as prayer, fasting, and charity. Strive against your lower self to become obedient so that acts of worship become beloved to you, and exert effort in supplication, and keep company with righteous people. Undertake as much good work as you are able to and persevere in it so you do not grow weary, for the most beloved deeds to Allah are those performed consistently.