Selena Gomez and Her '4' Besties Get Inked

Madison De La Garza says she's "so thankful that I can tell her happy birthday" after Lovato's recent overdose.

Demi Lovato's younger sister is feeling thankful today, her sister's 26th birthday, following the singer's recent relapse and hospitalization.

Madison De La Garza shared a throwback photo of her and Lovato together from their childhood, taking time to celebrate her sister's special day and thank everyone who helped Demi recover from her overdose.

"Today could have been one of the worst days of my life, but instead I get to spend it thanking God, the incredible doctors, Demi's team, and everyone across the world who offered their support," wrote the 16 year old. "Without all of these people I wouldn't have my big sister anymore."

"I've been thinking about how I wish that everyone could see the silly little things that she does, like how her nostrils move when she says certain words and when she brushes my hair behind my ear when I'm trying to sleep, because those are the things I'm thankful for today," she continued. "They seem so small, but those little things make up my sister - not a singer, not a celebrity, and definitely not what she's been described as in the media - she's a daughter, a friend, and my big sister ... and I am so, so thankful that I can tell her happy birthday."

Earlier this month, Lovato spoke out about her overdose after being admitted to the hospital on July 24.

"I have always been transparent about my journey with addiction. What I've learned is that this illness is not something that disappears or fades with time. It is something I must continue to overcome and have not done yet," she wrote at the time. "I want to thank God for keeping me alive and well. To my fans, I am forever grateful for all of your love and support throughout this past week and beyond. Your positive thoughts and prayers have helped me navigate through this difficult time."

"I want to thank my family, my team, and the staff at Cedars-Sinai who have been by my side this entire time. Without them I wouldn't be here writing this letter to all of you," she continued. "I now need time to heal and focus on my sobriety and road to recovery. The love you have all shown me will never be forgotten and I look forward to the day where I can say I came out on the other side."

"I will keep fighting," Lovato, who is currently seeking treatment in rehab concluded.