Grab a tissue. Miley Cyrus is having the worst week of her life — including the second and third worst days of her 21-year-old existence, the pop star revealed on Twitter.

Miley is grieving over her dog, Floyd, who died Tuesday. But the show must go on, and Miley gamely continued her "Bangerz" tour — but not without tears. Performing Fleetwood Mac's "Landslide" in Boston, the pop star choked up and cried during a soundcheck Wednesday.

"I just want to do this song for [Floyd] 'cause we used to always listen to Fleetwood Mac together," Cyrus said. "It was his favorite song to go on runs to."

You can see Miley's emotional performance in the videos below — choose the first for better sound quality, and the second for better pictures:

Cyrus has been tweeting since April 1 about Floyd's death, discussing her emotions in detail.

Today is the 2nd worst day of my life

— Miley Ray Cyrus (@MileyCyrus) April 1, 2014

I don't wanna say it because I don't want it to be real... But my precious baby Floyd has passed away I am broken pic.twitter.com/QBPujurnUj

— Miley Ray Cyrus (@MileyCyrus) April 2, 2014

I know I don't mean it but I wish he would've taken me with him this is unbearable. What am I gonna do without him? pic.twitter.com/Jq9HEvBsw6

— Miley Ray Cyrus (@MileyCyrus) April 2, 2014

I'm sorry in advance if I am not myself tomorrow Boston. I will try my best to be my best

— Miley Ray Cyrus (@MileyCyrus) April 2, 2014

I miss him so much

— Miley Ray Cyrus (@MileyCyrus) April 2, 2014

what you don't understand is he's not in a better place the best place he could be was with me... where he was loved more than anything

— Miley Ray Cyrus (@MileyCyrus) April 2, 2014

this is the 3rd worst day of my life. I am beyond miserable.

— Miley Ray Cyrus (@MileyCyrus) April 2, 2014

Didn't think there could be a day shittier than yesterday or the day before that... then I woke up this morning.

— Miley Ray Cyrus (@MileyCyrus) April 3, 2014

I'm fucking miserable

— Miley Ray Cyrus (@MileyCyrus) April 3, 2014

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Miley Cyrus's Guide to Owning Your 21st Birthday

1. 1. Don't stress about the details.

   Do you have a group of friends and a way to procure alcohol? Then you'll be good. Relax.

   Image: Tumblr perezhilton

2. 2. Take care in selecting your accessories.

   The right glittery clutch, or grill, could make the difference.

   Image: Tumblr candelabelieber07

3. 3. But don't wear an outfit that's easily destructible.

   You don't want to wear the dress that slips off or the heels that always catch on tiles, this is not a night for wardrobe malfunctions.

   Image: Tumblr wherever-miley-go

4. 4. Do something crazy.

   Trying a weird looking drink crazy, not rob a liqueur store crazy.

   Image: Tumblr h0w-idol

5. 5. Think about seeing the Instagram pictures in the harsh light of day.

   It should keep you from doing anything too dangerous.

   Image: Tumblr whatshouldbccallus

6. 6. You can never wear enough body glitter.

   It's your birthday, and you can sparkle if you want to.

   Image: Tumblr hoodiesallen

7. 7. Rest up before your night out.

   It's your birthday and no one can fault you for claiming an afternoon nap.

   Image: Tumblr shabbitable

8. 8. Don't try to live up to other people's expectations.

   This is your night, and whether you want it too] look like The Hangover or not is your decision.

   Image: Tumblr dailymileyyyy

9. 9. Bring snacks.

   Because sometimes the difference between tipsy and drunk is a bag of goldfish.

   Image: Tumblr mileyjaneholland

10. 10. It's fine to be excited, but maintain realistic expectations for your night.

    You're going to have fun, but it probably won't be the best night or your life. But that's good, because you have a lot of birthdays left.

    Image: WeHeartIt alexandra_schiller

11. 11. Don't let minor set backs ruin your whole night.

    Even if the perfect bar is packed or they're out of your favorite drink, it's going to be ok.

    Image: Tumblr mylifeisovernow

12. 12. Occasionally stick your tongue out.

    Hey, it works for Miley.

    Image: Tumblr wizboh

13. 13. Go out with a group that makes you feel comfortable.

    It's very possible you're going to have to trust these people to keep you from making terrible decisions. So ask yourself -- would they let you do it for the vine?

    Image: Tumblr sylphiia

14. 14. Realize when it's time to go home.

    Image: Tumblr torvnto