The Bible is applicable to everyone in every circumstance and it certainly can encourage when you are feeling down!
I read Psalms chapter 55 and verse 22 jumped out at me:
"Cast your burden upon the Lord and He will sustain you: He will never allow the righteous to be shaken."
No matter what is going on in your life (and it may be a whole lot worse than feeling tired and getting a headache) God is willing to take your burden and care for you. Trust Him in that.
I happened to glance over the next couple of chapters and I noticed the verses they had underlined- they were also very encouraging ones so I will also share them with you.
"When I am afraid, I will trust in You. In God, whose word I praise, In God I have put my trust; I shall not be afraid. What can mere man do to me? Psalms 56:3 & 4
"I will cry to God Most High, To God who accomplishes all things for me." Psalms 57:2
God is always there- through good times and bad, in joy and in sorrow- He is there! Seek Him.