On Sunday, Bella shared a handful of meaningful photos ... you see wires connected to her body while laying in a hospital bed, nurses by her side, and even some blood, too.

Bella spells out the mental anguish Lyme disease has taken on her ... "Living in this state, worsening with time and work while trying to make myself, my family and the people who support me, proud, had taken a toll on me in ways I can’t really explain."

She continues ... "To be that sad and sick with the most blessings/privilege/opportunity/love around me was quite possibly the most confusing thing ever."

With that said, Bella is feeling optimistic for the first time in a while ... saying the treatment was well worth it if she can now live her life to the fullest for the first time ever.

Bella also gives a big shout-out to her mother, Yolanda -- who also has Lyme disease -- for keeping all of her medical records and sticking by her side through the whole process.

You'll recall ... Bella and her brother, Anwar, were both diagnosed with Lyme disease in 2012. Bella shared a letter from her doctor dated back to 2014 ... saying she was suffering from fatigue, depression, headaches, and night sweats, among other things.